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Gastrointestinal stromal tumor (GIST) is the most frequent spindle cell tumor in the gastrointestinal tract and may arise from esophagus to rectum. The stomach is the most frequent site, followed by small intestine, rectum, and esophagus. There have been some regional differences reported in their histopathologic and clinical presentations. The purpose of this study is to compare ultrastructural features of GIST, according to its anatomic site, in order to provide additional data to support the current concept of its histogenesis. Fifty-four GISTs (27 from stomach, 23 from small intestine, and 4 from rectum) were included in the study. Histopathologically, gastric GISTs tended to be more frequently epithelioid, particularly those in children, while small intestinal GISTs (SISTs) were mostly spindly in all but three cases. All four of the rectal GISTs were spindly. Ultrastructurally, there seem to be considerable regional differences. In the majority of gastric GISTs, in both epithelioid and spindle types, tumor cells exhibited focal features of myoid differentiation evidenced by the presence of incomplete external lamina (EL) and/or focal accumulations of thin fibers with interrupted electron densities consistent with actin filaments. However, features of myoid differentiation were exceptional for SISTs and rectal GISTs, being present in only one example in each. Some gastric GISTs, particularly those having an epithelioid appearance, showed cell borders luxuriously decorated by long filopods (anemone cell features). Anemone cell features were also present in spindle cell types of gastric GISTs as well as SISTs, albeit it was simpler and less luxuriant. Skeinoid fibers were present in the majority of SISTs and rectal GISTs, but absent in all gastric GISTs except one. These differences appeared to be too significant to propose a uniform histogenesis for all GISTs. Nevertheless, on closer analysis, certain features could be identified to explain a line of differentiation in all GISTs ranging from (1) polygonal uncommitted epithelioid mesenchymal cells with cell borders decorated by luxuriant fimbria, to (2) spindly tumor cells with less prominent fimbria, or (3) cells with or without features of minimum myoid differentiation characterized by the focal presence of cytoplasmic actin fibers or incomplete EL or skeinoid fibers, which might represent an altered product of EL protein. These findings led the author to speculate that the probable primordial cells of GIST may be the primitive mesenchymal cells, which have the potential to differentiate into myoid cells. In this regard, it is important to note that the putative primordial cell of GIST, interstitial cells of Cajal (ICC), and intestinal smooth muscle cells have been shown to develop from the common progenitor cells of the primitive gut, and c-Kit plays a crucial role in the determination of their fate to differentiate to muscle cells or ICC. The author concludes that all GISTs derive from stem cells in the gut retaining some of the differentiation potential seen in primitive gut cells. One of the likely candidates for such cells in the intestinal musculature is ICC-DMP (interstitial cells of Cajal associated with deep muscular plexus) identified as ICC having smooth muscle features identified exclusively by electron microscopy. These cells have been shown to have some of the features of muscle cells by the presence of external lamina and less well-organized cytoplasmic filaments; they also express CD117 in the cytoplasm. Furthermore, recent studies demonstrated the presence of so-called progenitor cells of ICC, similar to ICC-DMP in appearance, expressing insulin-like growth factor and CD34, indicating their stem cell nature. The author proposes that all GISTs develop from the common progenitor cells similar to primitive gut cells, which may differentiate into tumor cells with more myoid features in the stomach (similar to so-called ICC-DMP) as well as spindle cells with less myoid features (similar to ICC-MP [interstitial cells of Cajal associated with the myenteric plexus] in the small intestine and rectum). ICC-DMP have been recruited in the group of ICC by electron microscopic technique alone without methylene blue stain and it is questionable whether they are part of ICC depicted by the ICC network originally shown by Dr. Cajal more than century ago. Recent discovery of their expression of insulin-like growth factors may indicate that they represent persisting primitive gut cells (gut stem cells), which may serve as the progenitor cells to GIST. It is also pointed out that in this era of ICC and GIST pandemonium, a minority of intestinal stromal tumors with mature smooth muscle features have been totally ignored; these now appear to belong to GISTs, representing the best differentiated example among the tumors developing from the same progenitor cells.

The purpose of this study was to evaluate cyclooxygenase-2 (COX-2) expression in the successive steps of breast carcinogenesis and to determine its correlation with HER-2/neu and p53 expression in invasive ductal carcinomas of the breast. Immunohistochemical staining with anti-COX-2 antibody was performed in normal breast tissue, usual hyperplasia, ductal carcinoma in situ, and invasive ductal carcinoma. Expression of COX-2 in invasive ductal carcinoma was correlated with immunohistochemical expression of HER-2/neu and p53 protein. COX-2 expression was found to be progressively elevated along the continuum from normal breast tissue to invasive ductal carcinoma (P0.001). COX-2 expression significantly correlated with p53 and HER-2/neu protein expression (P0.05 and P0.001). On multivariate analysis, only TNM stage and elevated COX-2 expression correlated with survival. Our results suggest that COX-2 may be involved in the carcinogenesis of the breast and may be an independent prognostic indicator in patients with invasive ductal carcinoma. HER-2/neu and p53 are likely to be involved in the regulation of COX-2 expression in invasive ductal carcinomas of the breast.

Ossifying fibromyxoid tumors (OFMT) are rare soft tissue tumors of uncertain histogenesis and clinical behavior. Since Enzinger, Weiss, and Liang first described 59 examples in 1989 (Am Surg Pathol. 13:817-827), approximately 150 cases have been reported. Their clinicopathologic features are fairly well characterized and their histogenesis remains unknown. Three examples of soft tissue tumors with typical histopathologic characteristics of OFMT were studied: case 1, a 43-year-old female with a 2.5-cm tumor of the back; case 2, a 56-year-old man with an 8-cm thigh mass; and case 3, an 81-year-old female with a 13.5-cm buttock tumor. For immunohistochemistry, formalin-fixed, paraffin-embedded tissue sections were stained with antibodies against cytokeratin, smooth muscle actin, desmin, vimentin, S-100 protein, EMA, and collagen type IV using standard ABC-peroxidase methods. For electron microscopy, tissue samples fixed in EM-grade buffered formalin were processed according to routine methods. Immunohistochemistry showed that the tumor cells were positive for vimentin and S-100 protein in all 3 cases. Stains for collagen type IV revealed diffusely positive staining in the stroma with a tendency for stronger staining around the cell borders in 2 out of 3 cases. Desmin was positive in one and actin was positive in one other case. By electron microscopy, tumor cells were characterized by centrally located round to oval nuclei with varying amounts of cytoplasm containing scanty cytoplasmic organelles. There were rare profiles of rough-surfaced endoplasmic reticulum (RER) and rare mitochondria with areas of condensed intermediate filaments. No tonofilaments or actin filaments were present. There were multiple short web-like processes, some of which were attached to that of neighboring cells by primitive cell junctions. In all 3 cases, lesional cells showed external lamina (EL), which was abundant in case 1, forming redundant scrolls frequently. In case 2, EL was less prominent and incomplete, and interrupted portions of EL were present only along the periphery of cell columns or nests bordering the stroma. In case 3, which behaved as a malignant tumor, the tumor cells were less differentiated spindle cells with primitive cellular features, and EL was rarely found along the short span of tumor cell borders. In this study, tumor cells in OFMT were polygonal to stellate often with multiple short cytoplasmic processes. The tumor cells were found to form cell clusters attached by primitive intercellular junctions between cytoplasmic processes forming intercellular bridges. The cell borders facing the stroma around cell clusters tended to be flat and had incomplete EL, while no EL was present along the cell borders facing the inner aspect of cell clusters. These ultrastructural findings together with immunophenotypic expression of S-100 protein presented closer resemblance to those of modified myoepithelial cells in pleomorphic adenomas of salivary glands and skin appendages rather than peripheral nerve sheath tumors. The authors conclude that these findings render more support to the hypothesis of myoepithelial histogenesis of OFMT. They also conclude that ultrastructural study not only helps accurate diagnosis, but also may aid in predicting malignant behavior by the degree of deviation from the typical examples of OFMT.

Tumor diagnosis mainly depends on the appearance of the tumor cells in recapitulating the appearance of primordial cells from which they arise. However, certain tumors may present with specific stromal changes that may assist/enhance the diagnosis. In this presentation, diagnostic stromal features have been reviewed. The cytoplasm is enclosed by a unit membrane, which serves as a barrier to, as well as an interface with, surrounding structures. Epithelial cells usually show characteristic basal-apical orientation. In mesenchymal tissue, different types of interface can be found in different types of mesenchymal tissue. External lamina can be defined as an anatomic structure, which encloses anatomic functional units. In epithelial tissue, cells in a functional unit are enclosed within a well-defined external lamina (EL). In malignant epithelial tumors, EL can become increasingly indistinct as tumors become less differentiated, and one has to look for it diligently. Within the external lamina, epithelial cells are closely packed with closely apposed cell membranes and cell attachment junctions. In contrast to epithelial tissue, mesenchymal tissue is usually characterized by the stromal elements they produce. Individual cells are embedded in the stroma, and individual mesenchymal cells represent the functional unit. Vascular endothelial cells are an exception since their relationship to stroma resembles to that of epithelial cells. Thus, tumors deriving from mesenchymal cells known to have external lamina such as muscle cells and Schwann cells tend to show total enclosure of cells by external lamina. In malignant muscle tumors, external lamina production can be focally present and found only by diligent search. In Schwann cell tumors, the presence of EL is prominent in low-grade tumors and more irregular and variable in malignant tumors. In the latter, stromal aggregation of scrolls of external lamina can be characteristic. Similar features are seen in ossifying fibromyxoid tumors. Fibronexus junctions (composed of extracellular fibronectin fillements linking intracellular 5-nm filaments) is claimed to be typical of myofbroblasts. Finding them in spindle cell tumors justifies a diagnosis of myofibroblastomas. There have been several stromal changes diagnostic for certain tumors found only by electron microscopy. Fibrous long-spaced collagen (known as Luse bodies) is diagnostic for peripheral nerve sheath tumors, but they can rarely be found in other tumors. Luse bodies usually appear as focally as crystallized aggregates apart from the regular collagenous interstitial stroma. They should be distinguished from other nonspecific long-spaced collagen changes. The changes are diffusely stromal in contrast to Luse bodies. Spiny collagen and amianthoid fibers are interesting collagen fibrils and their diagnostic value is questionable. Skeinoid fibers (SF) are short-spaced collagen of 41- to 45-nm banding so-named because of their peculiar appearance by electron microscopy simulating skeins of yarn. They were originally described in neurogenic tumors and small intestinal stromal tumors with features of gastrointestinal autonomic nerve tumors (GANT). Although there have been a few sporadic case reports of the presence of skeinoid fibers in nonneurogenic tumors, the frequent presence of SF in spindle cell tumors signifies their neurogenic nature in this authors' experience. An exception to this is that SF can be a constant element of rare ciliary body tumors known as ciliary mesectodermal leiomyomas, in which tumor cells show some resemblance to smooth muscle as well as Schwann cells. In addition to SF, several other types of peculiar crystallized collagen were observed in GANT tumors, particularly those with multiple tumor syndromes such as neurofibromatosis and Carney's triad. They simulate the appearance of railroad tracks or centrosomes. The reason for this is not known. The authors speculate that such collagen crystallization may be caused by genetic alterations involving collagenosis. Further studies will be necessary to clarify their pathogenesis. Another peculiar stromal change is electron-dense stromal filamentous aggregates with extra-long banding of > 250-nm periodicity previously described in Ewing sarcomas. This stromal change simulating a tiger skin pattern is also seen in primitive neuroectodermal tumors and malignant melanomas. In view of continually new discoveries of stromal changes that can be used for the differential diagnosis of tumors, the importance of close evaluation of stromal elements of tumors, and diligent application of electron microscopy in tumor diagnosis cannot be overemphasized.

Objective . The purpose of this study is to evaluate a modified MonoPrep2™ (MP) of liquid-based cytology (LBC) to search for a less expensive alternative technique usable for screening of cervical cancers. Study design . Cervicovaginal direct-to-vial samples from 1218 consecutive patients were processed with the modified MP technique and the results were compared with those of currently popular ThinPrep® Pap test (TP) technique. Results . Both MP and TP methods provide uniformly spread thin layers of cells without cellular overlap or significant obscuring elements. The diameter of the circular area was 20 mm in MP and 22 mm in TP. Obscuring factors were slightly more frequent in MP but not enough to affect interpretation. Thirteen specimens were excluded from the study because of poor specimen quality in MP. In 1205 patients, there was an absolute agreement in results (the Bethesda diagnosis system) between the two methods, and discordances were observed in only 18 (1.5%) in 1187 cases (98.5%). Furthermore, there was no significant difference in diagnostic accuracy in histopathologic correlation between the two methods. The sensitivity of MP was slightly lower than that of TP, and the specificity of MP was higher than that of TP. A human papillomavirus (HPV) test with polymerase chain reaction (PCR) using broad-spectrum probes has yielded good results in both MP and TP samples. Conclusions . The modification of the MP method gave comparable results to those of TP in terms of smear quality, cytologic diagnostic evaluation, and biopsy correlation with much less cost. The modified MP offers a cost-effective alternative to the currently popular expensive techniques of liquid-based cytology practical for cervical cancer screening.

The role of COX-2 expression and angiogenesis of lung cancer is yet to be delineated. Eighty four non-small cell lung cancer (NSCLC) specimens were evaluated for COX-2 expression, microvessel density (MVD), and vascular endothelial growth factor (VEGF) expression by immunohistochemical methods. The relationships between COX-2 expression and MVD, VEGF expression, and survival time were analyzed. COX-2 expression was observed in the cytoplasm and membrane of the carcinoma cells, and premalignant cells. COX-2 was positive in 67 cases (79.8%). There was a statistically significant correlation between COX-2 expression and tumor size, TNM stage, tumor type, VEGF expression, and vascular pattern with survival in univariate analysis. No significant correlation was seen between COX-2, VEGF expression and MVD. A lack of expression of either COX-2 or VEGF expression or both, however, was associated with lower MVD than the group with both expressed. The difference was statistically significant (P=0.005). Statistically significant differences were also observed according to TNM stage, vascular pattern, COX-2 expression, and VEGF expression. With multivariate analysis, only TNM stage and COX-2 expression retained their significance as independent predictors of survival. COX-2 expression takes part in tumor angiogenesis and is a significant poor prognostic factor in the surgically resected NSCLC. COX-2 inhibitor, either in combination therapy with other agents, or for chemoprevention, may be effective via suppression of angiogenesis in this fatal disease.

A case of postirradiation epithelioid angiosarcoma of the breast in a 72-year-old woman is reported. She had had right breast conserving surgery, axillary lymph node dissection, and 50 Gy external beam radiation therapy for infiltrating ductal carcinoma. A skin lesion on the irradiated breast appeared 5 years after completion of radiation. Angiosarcoma was diagnosed in a contralateral axillary mass 8 months later. Light microscopically, the tumor was characterized by a sheet-like growth of epithelioid cells with focal vasoformative areas. Tumor cells were reactive for factor VIII-related antigen, cytokeratin and CD34. Electron microscopically, the tumor cells were round with smooth cell borders. They were closely apposed, occasionally forming a small lumen containing single red blood cells or aggregates of platelets. Groups of tumor cells were enclosed by an external lamina. The tumor cells had abundant cytoplasm with sparse organelles. Rare suggestive Weibel-Palade bodies were present. The immunohistochemical and ultrastructural findings in this postirradiation tumor were in agreement with previously reported findings in non-irradiation-induced epithelioid angiosarcomas.

Neurofibromatosis type 1 could be associated with multiple gastrointestinal stromal tumours, although their presence is not considered among the major diagnostic criteria. We present here a case of a 50-year-old female complaining of abdominal pain, with about 100 small intestinal stromal tumours. This finding prompted us to suspect a neurofibromatosis which was clinically confirmed afterwards. Light microscopy examination revealed a low-grade stromal tumour with skeinoid fibres. Mixed neural-interstitial cells of Cajal origin or, alternatively, neural differentiation of interstitial cells of Cajal are discussed on the basis of immunophenotype (CD117+, CD34+) and ultrastructure. A 2-year follow-up did not indicate an aggressive course in the case of this neoplasm.

Neuroendocrine tumors may derive either from neuroectoderm or endoderm. Both may present with a similar histologic pattern known as "Zellballen" regardless of their histogenetic origin, making it difficult to separate the two different histogenetic entities in certain cases. To evaluate the usefulness of sustentacular cells in the recognition of tumors of paraganglionic origin, the authors analyzed immunohistochemical and ultrastructural characteristics of 25 paragangliomas and 19 pulmonary and 10 small intestinal carcinoids. Sustentacular cells with characteristic dendritic features, strong immunoreactivity for S-100 protein, and agranular cytoplasm by electron microscopy were found consistently in the paragangliomas and not found in typical carcinoid tumors, except for four examples of spindle cell carcinoid of the lung. The presence of sustentacular cells in tumors with "Zellballen" pattern therefore denotes paraganglionic origin.

Background. Extragonadal endodermal sinus tumors arising in the external genitalia represent an exceedingly rare malignancy in women. Six cases of endodermal sinus tumors of the vulva have been reported to date, with three cases failing to respond to conservative surgery and vincristine-based chemotherapy. We report a seventh case of vulvar endodermal sinus tumor that was treated with radical surgery and platinum-based chemotherapy. Case. RT is an 18-year-old female who presented with a vulvar mass that was diagnosed as endodermal sinus tumor at the time of biopsy. She was subsequently treated with modified radical vulvectomy and ipsilateral groin lymphadenectomy, followed by bleomycin, etoposide, and cisplatin chemotherapeutic regimen. She has since remained free of disease for 18 months as evidenced by serum α-fetoprotein and physical exam at 18 months. Conclusions. Vulvar endodermal sinus tumors represent a very small number of germ cell tumors in women. Based on the previous accounts, this disease appears to be more fatal than endodermal sinus tumor arising at other sites. These tumors also have a predilection for local metastasis. Due to the previous accounts, we chose to treat this patient with radical surgery and platinum-based chemotherapy. This treatment regimen has resulted in a disease-free state for 18 months.

Solitary fibrous tumor (SFT) is a rare neoplasm that, in addition to its classic presentation as a pleural-based mass, can also be encountered in unusual sites. The main difficulty in making the diagnosis of SFTs results from the unfamiliarity with its diverse clinical and pathologic features. This series of SFTs, some with unusual clinicopathologic presentation, included nine women and two men, ranging in age from 28 years to 74 years (five in pleura, one in lung parenchyma, one in breast, and four in mediastinum). The tumors were locally excised in eight cases and were resected along with portions of lung parenchyma in three. A panel of immunohistochemical stains was used to characterize these tumors. They were all vimentin-positive and, with the exception of one case, CD34-positive. Tumors were negative with antibodies directed against cytokeratin, factor VIII-related antigen, S-100 protein, muscle-specific actin, and smooth-muscle actin. Various diagnoses were initially rendered for these clinically and pathologically diverse lesions by the examining pathologists. Awareness of the various gross and microscopic patterns of these tumors, the possibility of occurring in unusual sites, and the use of immunohistochemical stains, particularly CD34, should eliminate most of the difficulties in arriving at a correct diagnosis. One patient died of metastatic breast cancer; all other patients were alive and well with a median follow-up of 17 months.

Although clear cells resembling oligodendrocytes are known to occur in ependymomas, tumors composed primarily of such cells, i.e., clear cell ependymoma (CCE), are rare. Herein we characterize the clinicopathologic features of eight examples of CCE encountered at Mayo Clinic from 1983 to 1996. The tumors occurred in patients 3-31 years of age and presented as well-demarcated, deeply situated, contrast-enhancing masses, all of which were supratentorial. All but one case lacked classic light microscopic features of ependymoma. Although nearly all were immunoreactive for glial fibrillary acidic protein, it was electron microscopy that showed the diagnostic hallmarks of ependymoma, including complex intercellular junctions, surface microvilli and cilia, and microrosette formation, thus underscoring the importance of electron microscopy in the diagnosis of clear cell ependymomas. The differential diagnosis of CCE includes not only oligodendroglioma, but central neurocytoma and glioneurocytoma. Unlike oligodendrogliomas, CCEs are characterized by their sharp circumscription, hypervascularity as reflected in contrast enhancement on computed tomography and magnetic resonance imaging, their noninfiltrative pattern of growth that displaces parenchyma, and the occasional formation of vague perivascular pseudorosettes. Unlike central neurocytomas and glioneurocytomas, CCE lack secretory granules, vesicles, and synapses by electron microscopy and neuroendocrine markers by immunocytochemistry. In summary, the diagnosis of CCE requires neuroimaging, histologic, and ultrastructural correlation. The latter is essential in a limited biopsy. Ultrastructural studies also play a role in identifying glioneurocytomas. CCEs behave like more ordinary ependymomas. The importance of their recognition is the avoidance of alternative diagnoses and inappropriate therapies.

Background Several studies have indicated an etiologic role for viruses in the development of sinonasal inverted papillomata (IP). A recent report demonstrates a strong relationship (65%) between Epstein-Barr virus (EBV) and these lesions using polymerase chain reaction (PCR) analysis. Methods The present study analyzes a series of paraffin-embedded tissues, comprising 25 surgically resected IPs and four fungiform papillomata (FP) for the presence of EBV using a sensitive in situ hybridization (ISH) assay and PCR. Results None of the specimens examined showed evidence of EBV infection by ISH, and only two papillomata (one sinonasal IP and one FP) gave positive reactions for EBV using PCR. Conclusions These data challenge the previous report and suggest that EBV is not a significant etiopathologic factor to be considered in the development of sinonasal IP. © 1997 John Wiley & Sons, Inc. Head Neck19: 98–106, 1997.

One hundred and thirty-seven consecutive cases of gastric carcinomas were evaluated for the presence of Epstein-Barr virus (EBV) by use of an in situ hybridization (ISH) assay for EBV-encoded RNA (EBER1) transcript and by means of the polymerase chain reaction (PCR) to amplify the internal repeat segment of the EBV genome. EBER1 was localized in tumor nuclei of 6 (4.3%) specimens, 5 of which were lymphocpithclioma-like carcinomas. Forty-five cases (32.8%) were positive by PCR, but evidence suggests that EBV positivity in many of these cases was due to latently infected lymphocytes. The presence of EBV by ISH was strongly associated with increased lymphocytic infiltration of tumors. Our inability to identify significant correlations between EBV-infected tumors and patient age, gender, or ethnicity, and tumor stage or histologic type was partly thwarted by low numbers of ISH-positive cases. Int J Surg Pathol 4(3):00-00, 1997

Epstein-Barr virus (EBV)-associated gastric carcinomas have been reported from various regions of the world. Epstein-Barr virus appears to be pathogenetically related to some gastric carcinomas. To determine the incidence of EBV association with gastric carcinomas among Koreans, the authors have studied EBV genome expression in 89 consecutive patients with gastric carcinomas diagnosed at the Catholic University Hospitals in Seoul, Korea, using in situ hybridization (ISH) for EBV-encoded small RNAs (EBERs), and immunohistochemistry for EBV latent membrane proteins (LMP) and CD21 antigen on paraffin sections. Thirty-seven gastric specimens with benign ulcer disease were used controls. EBV-encoded small RNAs were expressed in tumor cell nuclei in 12 patients (13.5%). None of the controls or benign portions of the cases were positive. In the positive cases, all tumor cell nuclei were uniformly stained and the staining intensity was strong. Immunohistochemistry for LMP was positive in 3 of 12 EBERs positive patients and none of EBERs negative patients. EBV latent membrane proteins was localized only in the lymphoid cells infiltrating the tumor in two patients, and tumor cells as well as infiltrating lymphoid cells in one patient. These results indicate that the rate of EBV association with gastric carcinomas in Koreans is relatively high and comparable to other Far Eastern Asian regions. The expression pattern in EBV-associated gastric carcinomas is similar to those of nasopharyngeal carcinomas in which clonality analysis using specific probes to the tandem repeat region of EBV yielded single episomal bands suggesting that EBV infection in EBV-associated gastric carcinomas are also clonal and pathogenetically related to the neoplasm. However, the mechanism of tumorigenesis remains to be elucidated.

Multinucleated giant stromal cells (MGSC) have been described in a variety of lesions of various anatomical sites. They are generally believed to be derived from fibroblasts or myofibroblasts. Their size and bizarre appearance may lead to an erroneous interpretation of infiltrating malignant cells, but they are regarded as reactive in nature. MGSC also seem to participate in a neoplastic process and form a part of tumors called giant cell fibroblastomas (GCF). In GCF, multinucleated giant cells are sparsely scattered throughout the tumor, which is composed of loosely arranged spindle cells. Thus far, no tumor composed of MGSC entirely, to the best of the authors' knowledge, has been reported. This study involved an 80-year-old female with an omental tumor, which is believed to represent the first case of tumor of MGSC. The patient developed abdominal pain; a large abdominal tumor measuring 18 x 15 x 5 cm by computerized tomography was found located between the left lobe of the liver, the transverse colon, and the greater curvature of the stomach. Although the tumor was adherent to the above organs and infiltrating the omentum, it was resectable. Grossly, the tumor was highly vascular and the surface was shaggy with no recognizable capsule. The cut surfaces were red to tan with frequent cystic spaces containing bloody material. Microscopically, the tumor cells were large and multinucleated (2-6 nuclei) with prominent nucleoli. The cytoplasm was abundant and stained amphophilic. These tumor cells formed moderately cellular sheets filling the spaces between the varying sized vessels. There was prominent vascularity throughout the tumor. DNA study by image analysis revealed aneuploidy peaks. On immunohistochemistry, the tumor cells were strongly positive for vimentin, moderately positive for actin along the periphery of the cytoplasm, and negative for cytokeratin, EMA, myoglobin, S-100, CEA, Factor XIIIa, HMB-45, and HAM56 and KP-1. Ultrastructurally, the cytoplasm contained rich profiles of RER with scattered lysosomes. The cell borders were slightly irregular with occasional subplasmalemmal densities facing loosely arranged collagenous stroma. The light microscopic, immunohistochemical, and electron microscopic features of tumor cells were remarkably similar to MGSC. The tumor size and gross appearance suggested a malignancy, but it was a diploid tumor and the patient remains disease free 5 years after a complete resection.

Carcinoid tumors have been an interesting clinical and pathological entity for pathologists because of their unique histopathologic pattern of "Zellballen" (cell ball) and the hormones they produce demonstrable by histochemical and biochemical methods, including immunohistochemistry, and the presence of cytoplasmic dense-core particles demonstrable by electron microscopy. Since carcinoid tumors were established as an entity more than a century ago by Oberndorfer, who was credited with coining the term "carcinoid," meaning carcinoma-like tumors, tumors presenting with similar characteristics have been reported in most of parenchymal organs, including lungs. Carcinoid tumors in the lungs usually occur as bronchocentric tumors and present with typical histopathologic characteristics of carcinoid tumors, but they may present with significant variation in their cellular compositions, in contrast to the midgut carcinoid tumors. In the latter, tumor cells are quite similar to enterochromaffin granule containing crypt cells, which are regarded as their progenitor cells. Currently, a similar histogenetic explanation is applied to all carcinoid tumors occurring elsewhere. The bronchus is one of the most common anatomic sites in which the carcinoid tumors occur. However, bronchial carcinoid tumors differ from the midgut counterparts in microscopic appearance, showing more variability in cellular shape and composition from the classical form of midgut carcinoid tumors. In the lungs, neuroendocrine cells (NEC) are normally found in two different ways. Firstly, they are found as randomly scattered single cells (Kultchitsky cells) similar to enteric counterparts, and, secondly, they are found in aggregates known as "neuroepithelial bodies" (NEB) usually found in the branching point of bronchi. Interestingly, they keep a close anatomic relationship with parasympathetic nerve structures and even form synapses. NEB are usually found in the early stage of fetal development and are claimed to play an important role in the branching of bronchi and regeneration of bronchial epithelial cells following tissue injury. They are claimed to play an important function as a chemoreceptor apparatus related to oxygen tension of the breathing air. To test the hypothesis that histopathologic variability found in bronchial carcinoids may be related to the fact that lungs are endowed with more than one type of NEC, the author reviewed 36 cases of bronchial carcinoids and found 8 cases in which tumor cells varied significantly from typical carcinoids in cell shape and arrangement. Tumor cells tend to be spindly with frequent presence of S-100-positive sustentacular cells. The latter was designated as type II carcinoid and the rest as type I. Ultrastructurally, tumor cells in type I exhibited features more typical for epithelial cells. The tumor cells were usually polygonal, forming closely packed cell masses, and cell membranes were closely apposed with frequent primitive cell junctions. The membrane-bound dense-core granules were of variable size and appearance and larger than those seen in type II in which the size of granules ranged from 160 to 350 nm. In 2 cases of type I, frequent cells contained myelin bodies similar to those found in type II alveolar cells. In 14 cases of type I tumors, tumor cells formed lumens into which microvilli were converging. In 5 cases, some areas showed increased cell size exceeding the usual limit of pathologist's comfortable range of small cells. In 2 cases, the tumor contained areas of adenocarcinoma. Tumor cells in type II were rather oblong and closely packed without any intercellular spaces and the majority of tumor cells contained dense-core granules typical for so-called P granules. These cells seem to give out slender cell processes containing a few dense-core granules. In rare foci, groups of thin cell processes aggregate where profiles of processes cut at different angles can be seen. In such areas one can recognize the profiles of microtubules in many of them. In one tumor, which was previously reported by the author (Ultrapath 2001;25:207), microtubule-containing dendrites were common, as seen esthesioneuroblastomas. They appeared similar to dendrites of neurons. In addition to these chief cells, there were variable numbers of agranulated cells usually found at the periphery of cell balls bordering the interstitium. Some of these cells contained large aggregates of polymorphic dense bodies. However, no definite premelanosomes were found in our series. The results indicate that there exist at least two different types of carcinoid tumors in the lungs and their immunohistochemical and ultrastructural characteristics are quite different. The type I tumors are quite similar to those found in the midgut and their histogenesis might be similar. The type II tumors showed rather definite neural features in their immunophenotypic and ultrastructural characteristics, which is difficult to explain by the same histogenesis applied to type I. We postulate that type II tumors have a different histogenesis from type I. They may derive from NEC of neuroepithelial bodies rather than Kultchitsky cells. In this regard, it is interesting to note the similarity between neuroepithelial bodies of the lungs and olfactory bulbs in their cellular composition and anatomic arrangement of epithelial cells and nerves, and the similarity between tumors they produce, bronchial carcinoid tumors in our type II and olfactory neuroblastomas. It is concluded that there are two types of bronchial carcinoid tumors having two different histogenetic pathways. Detailed analysis of the ultrastructural characteristics is the best and definite means to differentiate two types of pulmonary carcinoid tumors.

We report two cases of low-grade glioma in which multiple cellular components, including cells with dense-core granules consistent with "neurocytes," were identified on electron microscopic studies. The first patient was an apparently normal boy until the onset of seizures at age 10 months. Initially, the seizures improved with phenobarbital treatment, but good seizure control was never achieved. Computed tomographic scan at age 23 months showed a calcified, nonenhancing left parietal mass. This tumor was composed of sheets of cells with clear cytoplasm and round to oval nuclei. Mucinous intercellular material stained positively with periodic acid-Schiff, mucicarmine, and alcian blue stains. Foci of calcification were evident. The second patient was a 13-year-old boy with a left parasagittal parieto-occipital mass who presented with a 4-month history of seizures and declining school performance. The tumor was composed of sheets of astrocytes with dark, hyperchromatic, pleomorphic nuclei in a fibrillary and microcystic background. The tumor contained the pleomorphism seen in the adult variant of pilocytic astrocytoma, as well as the microcystic component seen in the juvenile variety. Ultrastructurally in both cases, there were occasional tumor cells having round to oval nuclei with moderate amounts of cytoplasm containing 150- to 250-nm-diameter dense-core granules. These cells were admixed with the majority of tumor cells, which in case 1 had the ultrastructural features of astrocytes and oligodendrocytes and in case 2 had features of protoplasmic or pilocytic astrocytes. Our cases bear superficial resemblance to dysembryoplastic neuroepithelial tumors; however, dysplastic ganglion cells are an essential component for that diagnosis, and there were no dysplastic ganglion cells in either of our cases. Cells containing dense-core granules (neurocytes) were found in both our cases by electron microscopy and appear to be a part of a neoplastic process. The significance of neurocytes in low-grade gliomas is not known. Cerebral tumors consisting of neuroblasts/neurocytes in toto or in part have been increasingly recognized in recent years, and our cases add to the spectrum of such neoplasms. (J Child Neurol 1995;10:219-226).

Forty-eight male rats were randomly separated into four groups: a control group, a group treated with anabolic steroids, a group treated with daily exercise, and a group treated with both steroids and exercise. At 6 weeks, biomechanical, ultrastructural, and biochemical testing was performed on the Achilles tendons of half of the rats in each group. The remaining rats continued in the experimental protocol, but steroid administration was discontinued. Similar testing was then performed on the remaining rats at 12 weeks. Testing showed ana bolic steroids produced a stiffer tendon that absorbs less energy and fails with less elongation; tendon strength was unaffected. Effects were entirely revers ible on discontinuation of the steroids. Light microscopic analysis revealed no changes in the appearance of the fibrils. No change in fibril diameter or shape was noted on electron microscopic analysis. Biochemical testing revealed no change in qualitative immunofluorescence staining with Type III collagen or fibronectin. Abuse of anabolic steroids is a widespread problem among com petitive athletes; consequently, complications after their use are seen with increasing frequency. Knowledge of the effects of these drugs on tendon and the muscu lotendinous unit may prove helpful in counseling ath letes who use anabolic steroids.

The sinonasal region is known to harbor several types of tumors that belong to the general category of "small" round cell tumors and offer considerable diagnostic challenges. This study evaluated 33 cases of such tumors by electron microscopy to characterize their ultrastructural features in conjunction with immunohistochemistry, in an attempt to define diagnostic criteria of various types. Electron microscopy was useful in the proper classification of tumors in 27 cases: esthesioneuroblastoma (EN), 12; undifferentiated carcinoma, 6; melanoma, 3; lymphoma, 3; melanotic neuroectodermal tumor, 1; rhabdomyosarcoma, 1; and pituitary adenoma, 1. In the remaining six cases, the ultrastructural features were those of poorly differentiated carcinomas. They usually exhibited some epithelial characteristics as well as neuroendocrine features by immunohistochemistry and electron microscopy. These tumors could be best described as poorly differentiated neuro-endocrine carcinomas (malignant neuroepitheliomas). The most controversial diagnostic problems existed between the tumors categorized as esthesioneuroblastomas and neuroendocrine (NE) carcinomas. Esthesioneuroblastomas were characterized by uniform round nucleated cells with variable amounts of dendritic processes containing numerous dense core granules ranging from 150 to 350 nm in the perikarya and dendritic processes. Dendritic processes contained longitudinally arranged neural tubules and revealed an occasional synaptic junction. In three of the 12 cases of EN, cells with the appearance of sustentacular cells were recognized by electron microscopy. The NE carcinomas usually consisted of closely packed round cells with scanty cytoplasm that lacked any feature of neuroblastic cells. The tumor cells in this category often were epithelioid in appearance and exhibited a varying degree of cytokeratin positivity. Neuron-specific enolase was also positive in all cases, further suggesting their neuroepithelial nature. The greatest difference between EN and NE carcinomas was the absence of sustentacular cells in NE carcinomas. Immunohistochemical and electron microscopic studies are essential in the differential diagnosis of EN and NE carcinomas, because their microscopic appearance is very similar. The study indicates that EM is useful in the diagnostic categorization of sinonasal tumors of uncertain nature, particularly when it is used in conjunction with immunohistochemistry.

OBJECTIVES (1) To determine whether the protein of the suppressor gene p53 accumulates in leukoplakia of the oral cavity in individuals who use snuff; and (2) to determine whether a correlation exists between the accumulation of p53 protein and the degree of epithelial dysplasia present in oral leukoplakia. DESIGN Retrospective analysis of archival tissue specimens. SETTING The University Hospital, a tertiary referral hospital affiliated with the Oklahoma University Medical Center, Oklahoma City, Oklahoma. PATIENTS In the first part of the study, biopsy specimens of leukoplakia from 12 persons who used snuff were compared with specimens from uninvolved oral mucosa of the same persons and with biopsy specimens from 12 nontobacco-using persons. In the second part of the study, accumulation of p53 protein was determined in 42 archival paraffin-embedded specimens from oral leukoplakia and correlated with the degree of epithelial dysplasia. METHODS Accumulation of p53 protein was assessed by immunoperoxidase staining with four different primary antibodies. Positive cells were counted in five consecutive high-power fields. RESULTS In part one, the average number of positive cells in the leukoplakia of snuff-users (21.89 +/- 4.33; mean +/- SE) was higher than that of normal-appearing mucosa (4.00 +/- 1.0; p < 0.05) and that of nontobacco-using controls (7.00 +/- 5.04). In part two, the average number of positive cells was higher in the moderately dysplastic (140.36 +/- 30.03) and severely dysplastic lesions (232.86 +/- 26.85) than in the mildly dysplastic lesions (14.53 +/- 3.33; p < 0.05). The correlation between the degree of epithelial dysplasia and the number of cells positive is strong (Spearman's correlation coefficient = 0.853). CONCLUSIONS The accumulation of p53 protein in leukoplakia of snuff-users is higher than in normal-appearing oral mucosa from both snuff-users and nontobacco-using controls. A strong correlation exists between the degree of epithelial dysplasia present in oral leukoplakia and the number of cells staining positive for p53. The accumulation of p53 protein holds potential as an intermediate end point in studies of chemoprevention of oral cancer.

The identification of the causative organisms of cat scratch disease (CSD) has been elusive. The demonstration of Warthin-Starry stain-positive pleomorphic bacilli in lymph nodes of patients with CSD and recent serologic and epidemiologic data suggest an etiologic role of Rochalimaea henselae in CSD. The authors studied lymph node biopsy specimens of 46 patients with illnesses clinically consistent with CSD and found pleomorphic bacilli in 15 (33%). The organisms were labeled by polyclonal rabbit antibodies induced by outer surface proteins of R henselae. This finding further supports the possibility of an important role of R henselae in the pathogenesis of CSD.

Expression of four biologic markers was studied in 69 cases of endometrial cancer to identify their association with cell type, decreased survival, and increased tumor metastasis. Cell types included endometrioid (n = 45), serous papillary (n = 16), and clear cell (n = 8). Immunohistochemical stains were employed to detect the presence of epidermal growth factor receptor (EGFR), HER-2/neu, p53, and proliferating cell nuclear antigen (PCNA). Analysis revealed that EGFR was expressed in 49%, HER-2/neu in 59%, p53 in 9%, and PCNA in 16% of tumor specimens. HER-2/neu overexpression was significantly associated with depth of myometrial invasion. p53 and PCNA immunoreactivity significantly correlated with nonendometrioid histology, although PCNA was less specific in labeling these less favorable cell types. EGFR immunoreactivity also significantly correlated with nonendometrioid cell types and tumor metastases at time of diagnosis. Seventy-seven percent of patients with metastatic disease were EGFR-positive versus 36% positivity in patients with no evidence of metastases (P < 0.002). For patients with endometrioid adenocarcinoma, evidence of EGFR overexpression decreased survival from 89 to 69% (P < 0.04). In the serous papillary and clear cell category, EGFR positivity decreased survival from 86 to 27% (P < 0.03). EGFR strongly correlates with tumor metastasis and patient survival in endometrial cancer. Altered expression of this oncoprotein may serve as a guide to prognosis and treatment in these patients.

Background. Overexpression of epidermal growth factor receptor (EGFR) has been reported in endometrial adenocarcinoma. Methods. A retrospective analytic study was designed to investigate its prognostic utility. Sixty-nine patients were studied with cell types that included endometrioid (n = 45), papillary serous (n = 16), and clear cell (n = 8). Patients' medical charts and survival data were reviewed. Assessment of EGFR overexpression was done at the protein level by the use of an anti-EGFR polyclonal antibody that reacts with the cytoplasmic membrane glycoprotein receptor in paraffin-embedded tissues. Results. EGFR was overexpressed in 34 (49%) patients in whom immunoreactivity was limited to neoplastic cells. Initial bivariate analysis revealed significant correlations between EGFR immunoreactivity and histologic grade (r = 0.44, P < 0.001), metastasis (r = 0.38, P < 0.001), cell type (r = 0.30, P < 0.01), myometrial invasion (r = 0.30, P < 0.01), and patient age (r = 0.30, P < 0.01). Multiple logistic regression analyses showed that EGFR overexpression and nonendometrioid cell types are two independent statistically significant markers for the presence of metastases. EGFR immunoreactivity can significantly predict myometrial invasion, but after controlling for the histologic grade, its ability of significantly predict invasion was lost. EGFR overexpression was shown to be a statistically significant predictor of survival, even after controlling for patient age, histologic grade, and cell type. Conclusions. Expression of this oncoprotein may serve as an independent prognostic indicator and a guide to therapy in patients with endometrial cancer.

The pineal gland is host to a spectrum of neoplasms. Those considered to be derived from or differentiating toward pineal parenchymal cells are rare. Traditionally, pineal parenchymal tumors (PPTs) have been divided into 3 types: pineocytomas, pineoblastomas, and mixed or transitional tumors. Their characterization has been far from adequate and no firm diagnostic criteria, light microscopic or ultrastructural, have been established. In an attempt to provide more precise prognostic diagnostic criteria, we undertook a detailed ultrastructural analysis of 17 PPTs and found them to exhibit light microscopic and ultrastructural features strikingly similar to those of pineal parenchymal cells in varying stages of development, ranging from undifferentiated primitive neuroepithelial cells to mature pineal parenchymal cells. We endorse classification of PPTs based on a combination of their light microscopic and ultrastructural features. Accordingly, PPTs can be divided into three categories: 1) pinealoblastoma, 2) PPTs of intermediate or mixed differentiation, and 3) pineocytoma, a tumor of mature-appearing pineocytes. In keeping with this classification, our 3 pinealoblastomas behaved as highly malignant tumors. A correlation of morphology and prognosis was less evident between intermediate tumors and pineocytomas, perhaps the result of considerable variation in surgical and other therapies. Evidence of neurosensory differentiation, a feature noted to a varying extent in all but the pineoblastomas, included club-shaped "nerve endings" in 7 tumors, small numbers of dense core granules in 8, clear vesicles in 7, and structures suggestive of synapses in 4. With the exception of 3 undifferentiated PPTs or pinealoblastomas lacking nerve endings, all pineocytomas exhibited some combination of these markers of neuronal specialization. In that the ultrastructural features of these PPTs were more indicative of their aggressiveness than was their degree of light microscopic differentiation or grade, we consider electron microscopy a useful adjunct, not only in diagnosis but also in therapeutic decision-making and prognostication.

BACKGROUND The detection of potentially highly curable low-grade bladder cancers by noninvasive techniques remains an unsolved problem. Conventional cytology detects such tumors with 50% sensitivity, and addition of DNA measurements to cytology only improves sensitivity incrementally. Tumor-associated antigens potentially offer an additional diagnostic marker. METHODS In this study, the M344 antibody against a tumor-associated antigen expressed mainly by low-grade tumor cells was tested for its sensitivity and specificity, alone and in combination with DNA ploidy and cytology. Voided urine samples from 69 asymptomatic control subjects, urines and bladder washings from 59 patients with cancer, and 195 symptomatic control patients were collected. Cells were double-labeled with M344 monoclonal antibody and Hoechst. Each case was blinded, and the number of positive cells was scored by two independent observers. RESULTS High-grade and low-grade transitional cell carcinomas (TCC) were detected with equal efficiency (78%, P < 0.001 versus symptomatic control patients). Urine samples proved higher specificity in detecting cancers. Patients being monitored for recurrence, but without current detectable cancer, were intermediates between control subjects and patients with cancer, suggesting that this marker also responds to dysplasia or field disease. Patients with outlet obstruction did not significantly differ from patients with previous TCC (P = 0.95). When combined with DNA ploidy measurements and cytology, the sensitivity for low-grade and high-grade tumors was 88% and 95%, respectively. CONCLUSIONS The M344 antibody potentially could improve the specificity and sensitivity of detection of low-grade bladder tumors in symptomatic and asymptomatic patients as well as monitoring for recurrence, therapeutic response, and assessment of individual risk.

Phenotypic biochemical markers of oncogenesis and differentiation were mapped in bladder biopsies to investigate changes that occur in bladder tumorigenesis and to identify markers for increased bladder cancer risk. Touch preparations from biopsy specimens from 30 patients were obtained from tumors, the adjacent bladder epithelium, and random distant bladder epithelium. Markers, including DNA ploidy, epidermal growth factor receptor (EGFR), and oncoproteins, were quantified in individual cells by using quantitative fluorescence image analysis. Cluster analysis revealed the markers fell into three independent groups: (i) G-actin and EGFR; (ii) ploidy, cytology, and p185 (HER-2/neu oncoprotein) (ERBB2); and (iii) p300, a low-grade tumor antigen. Each marker displayed a gradient of abnormality from distant field to adjacent field to tumor. Different patterns for each marker suggested a developmental sequence of bladder cancer oncogenesis; G-actin was altered in 58% of distant biopsies (vs. 0/6 normals, P < 0.001), ploidy and cytology were altered in < 20% of distant fields and approximately 80% of tumors, and the other markers were intermediate. Patterns of EGFR and p185 suggest low-and high-grade tracks diverge early (P < 0.05 by Mann-Whitney U test for EGFR and ANOVA for p185). In conclusion, this study shows that a sequence of phenotypic changes accompanies development and progression of bladder cancers. Biochemical alterations in cells of the bladder field are often detectable before abnormal pathology, and markers previously thought to be limited to tumors were found in the field. The hierarchy of expression may be useful in identifying high-risk patients, assessing completeness of response to therapy, and monitoring and predicting recurrence.

Twenty-four male rats were divided into four groups, with anabolic steroids and exercise as variables. Biomechanical tests and histological evaluations were performed. The results of the biomechanical tests suggested that anabolic steroids produce a stiffer tendon, which fails with less elongation. The energy at the time when the tendon failed, the toe-limit elongation, and the elongation at the time of the first failure were all affected significantly. Changes in the force at failure were not statistically significant. No alterations of structure were noted when the specimens were viewed with light microscopy. Alterations of the sizes of the collagen fibrils were noted on electron microscopy.

Microscopic appearances of spindle cell tumors of the gastrointestinal tract are suggestive of smooth muscle origin; however, they usually lack specific muscle cell features by electron microscopy and immunohistochemistry, thus justifying their designation as stromal tumors. The present report describes nine cases of small intestinal stromal tumors with eosinophilic stromal globules composed of tangles of curved fibers with crossbands simulating an appearance of skeins, designated as skeinoid fibers. Patients' ages ranged from 28 to 87 years; and four were male. The tumors presented as well-delineated mural nodules ranging from 1.8 to 13 cm in size, causing intestinal obstruction or hemorrhage. Four were in the duodenum, three in the jejunum, and two unspecified. Microscopically, seven were benign; one, to the largest, was definitely malignant and metastasized to the liver. Another, the second largest (7.5 cm), showed moderate atypia with two mitoses per 10 high-power fields. The light microscopic appearance, including immunohistochemistry, were typical for small intestinal stromal tumors. Skeinoid fibers were strongly periodate-Schiff's procedure-positive and stained blue with the trichrome stain. They appeared as a few micra-sized specks to large globules reaching a few millimeters. Skeinoid fibers were also found in three neurogenic spindle cell tumors (an acoustic neuroma, a neurofibroma, and a plexosarcoma of the mesentery), suggesting that such fibers are possible ultrastructural markers for neurogenic tumors and thus small intestinal stromal tumors with skeinoid fibers are neurogenic in origin.

Lymphoepithelioma of the nasopharynx is an undifferentiated carcinoma with prominent lymphoid infiltration. Histologically similar tumors have been documented in the skin, lung, thymus, salivary gland, tonsil, and uterine cervix. The authors report three cases of gastric carcinoma that were histologically and immunohistochemically similar to lymphoepithelioma. The patients were elderly white persons (61, 76, and 77 years of age); two of them had previous partial gastric resections for benign ulcer disease. The tumors were located on the lesser gastric curvature (two cases) and at a previous anastomotic site (one case) and measured 3, 4, and 7 cm in largest dimension. Grossly, each neoplasm was a raised plaque-like lesion with a central ulcer. Microscopically, all three tumors were similar, with poorly differentiated polygonal tumor cells scattered throughout a dense lymphocytic background. In a few areas, tumor cells formed ill-defined cords. In two cases, the neoplasms invaded the gastric muscle layer but had a well-delineated (pushing) margin. The tumor cells were immunohistochemically positive for AE3-defined keratin, confirming their epithelial nature. The lymphocytes were a mixture of UCHL-1-positive T cells and L-26-positive B cells. Portions of the Epstein-Barr virus genome were present in all cases, as detected by the polymerase chain reaction. The morphologic features of these cases are similar to those of lymphoepithelioma in other anatomic sites, and these tumors represent a unique subtype of gastric carcinoma.

The article describes novel stromal fibrillar aggregates found in three cases of neurogenic spindle cell tumor and eight cases of small intestinal stromal tumor. The aggregates were composed of tangles of curvilinear fluffy fibrils with a periodicity of from 41 to 48 nm with a staining pattern similar to that of collagen fibrils. The overall ultrastructural appearance simulated skeins of yarn, hence they are designated skeinoid fibers. No similar stromal fibers were found in more than 5000 other tumors studied. Their exclusive presence in neurogenic spindle cell tumors suggests the possibility that they are an ultrastructural marker for neurogenic spindle cell tumors and that the eight cases of small intestinal stromal tumors with skeinoid fibers may be of neurogenic origin.

We have investigated the ultrastructural characteristics of 16 cases of pineal germinomas and compared them with those of 18 cases of testicular seminomas. Glandular differentiation of tumor cells was found in both though it was more consistently noted in pineal germinomas than in testicular seminomas. This feature was interpreted to represent early carcinomatous transformation of germinoma cells. It not only explains the difficulties occasionally encountered in distinguishing germinoma and its anaplastic variant from embryonal carcinoma, but also has implications for our understanding of germ cell neoplasia, particularly the place of germinoma/seminoma in the nosology of such tumors.

Background and Objectives Loss of PTEN expression has been associated with tumor progression and adverse patient outcome. The purpose of this study was to evaluate PTEN expression in the successive steps of progression in cervical neoplasia and to determine its correlation with tumor angiogenesis and clinicopathologic features in squamous cell carcinoma of the uterine cervix. Methods Immunohistochemical staining with anti-PTEN antibody was performed in a total of 160 patients with 12 normal cervical epithelium, 63 cervical intraepithelial neoplasia (33 CIN I, 30 CIN III), and 85 cervical squamous cell carcinomas. Microvessels were immunohistochemically labeled with an antibody for CD34. Computerized image analysis was used to evaluate microvessel density (MVD). Results Reduced PTEN expression progressively increased along the continuum from normal epithelium to squamous cell carcinoma (P

To evaluate the expression of tumor suppressor gene phosphatase and tensin homologue on chromosome 10 (PTEN) in ovarian epithelial tumors and its correlation with tumor growth and clinicopathologic features in ovarian adenocarcinomas.Immunohistochemical staining with anti-PTEN antibody was performed in 54 adenocarcinomas and 23 borderline tumors of the ovary. The apoptotic cells were visualized by terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling, and proliferative cells were visualized by staining with Ki-67 antibody.Reduced PTEN expression was significantly higher among the adenocarcinomas than the borderline tumors (p0.001). Reduced PTEN expression in adenocarcinomas did not correlate with International Federation of Obstetrics and Gynecology (FIGO) stage. The Ki-67 index (KI) and apoptotic index were significantly higher in adenocarcinomas as compared with borderline tumors (p0.001). Tumors with reduced PTEN expression in ovarian adenocarcinomas had a significantly higher KI than those with normal PTEN expression (p0.01). By univariate analysis, FIGO stage and histologic type correlated with survival. However, FIGO stage was the only independent prognostic factor by multivariate analysis.Our results suggest that alteration of the PTEN gene may be associated with malignant transformation of ovarian epithelial tumors. The PTEN gene seems to be a negative regulator of cell proliferation in ovarian adenocarcinomas.

We show here (presumably for the first time) a special type of cell in the human and rat exocrine pancreas. These cells have phenotypic characteristics of the enteric interstitial cells of Cajal (ICC). To identify pancreatic interstitial cells of Cajal (pICC) we used routine light microscopy, non-conventional light microscopy (less than 1 mum semi-thin sections of Epon-embedded specimens cut by ultramicrotomy and stained with Toluidine blue), transmission electron microscopy (TEM), and immunocytochemistry. The results showed that pICC can be recognized easily by light microscopy, particularly on semi-thin sections, as well as by TEM. Two-dimensional reconstructions from serial photos suggest a network-like spatial distribution of pICC. pICC represent 3.3+/-0.5% of all pancreatic cells, and seem to establish close spatial relationships with: capillaries (43%), acini (40%), stellate cells (14%), nerve fibres (3%). Most of pICC (88%) have 2 or 3 long processes (tens of mum) emerging from the cell body. TEM data show that pICC meet the criteria for positive diagnosis as ICC (e.g. numerous mitochondria, 8.7+/-0.8% of cytoplasm). Immunocytochemistry revealed that pICC are CD117/c-kit and CD34 positive. We found pICC positive (40-50%) for smooth muscle alpha-actin or S-100, and, occasionally, for CD68, NK1 neurokinin receptor and vimentin. The reactions for desmin and chromogranin A were negative in pICC. At present, only hypotheses and speculations can be formulated on the possible role of the pICC (e.g., juxtacrine and/or paracrine roles). In conclusion, the quite-established dogma: "ICC only in cavitary organs" is overpassed.

Loss of PTEN expression has been associated with advanced stages of tumor. Tumor angiogenesis is involved in tumor progression. In breast cancer, a high frequency of mutations of the PTEN locus has been reported. However, the prognostic importance of PTEN expression and its correlation with angiogenesis in breast cancer have not been well established. Formalin-fixed, paraffin-embedded tissues from 99 women with a primary diagnosis of invasive ductal carcinoma were evaluated for PTEN expression by immunohistochemical methods. The microvessel density (MVD) was also studied by immunohistochemical labeling of endothelial cells with CD34 antibody. Computerized image analysis was used to evaluate MVD. Reduced PTEN expression was seen in 27.3% of invasive ductal carcinoma. The MVD ranged from 22.0 to 197.0, with a median value of 58.5 (65.4 +/- 27.9). Reduced PTEN expression correlated with lymph node status (P < 0.01), tumor grade (P < 0.05), and tumor-node-metastasis (TNM) stage (P < 0.05). There was a statistically significant correlation between reduced PTEN expression and increased MVD (P < 0.05). The mean MVD was higher in reduced PTEN-expressive tumors, irrespective of stage, compared with normal PTEN-expressive tumors with the same stage. On multivariate analysis, only TNM stage and reduced PTEN expression correlated with survival. Our results suggest that reduced PTEN expression may be an independent prognostic indicator in patients with invasive ductal carcinoma. PTEN loss may be associated with increased tumor angiogenesis.

A subset of midgut carcinoids (MCs) result in mesenteric angiopathy (MA) and bowel infarction as a consequence of vascular compression caused by extensive mesenteric sclerosis (MS). The goal of this study was to determine whether the level of expression of several fibrosing-related growth factors was related to the finding of MA and/or MS in MCs. Eighteen cases of MC, 6 with both extensive MS and MA (group I), 5 with extensive MS only (group II), and 7 with ordinary MS only (group III), were analyzed for immunoexpression of beta-catenin, transforming growth factor-beta 2 (TGF beta 2), nerve growth factor 2 (NGF2), fibroblast growth factor 2 (FGF2), insulin growth factor receptor (IGFR), and bone morphogenic protein 4 (BMP4) in formalin-fixed, paraffin-embedded sections. Standard immunohistochemical technique was used following antigen retrieval. Immunostaining was scored semiquantitively as the product of the percentage and intensity (0 to 2+) of the immunostaining, giving a possible range of 0 to 200. One-way analysis of variance and Mann-Whitney nonparametric analyses were used for statistical analysis. The mean scores of immunoreactivity of each factor in groups I, II, and III were as follows: 135, 174, and 147 for beta-catenin (cytoplasmic reactivity only); 106, 112, and 92 for TGF beta 3; 1.67, 32, and 36 for NGF-2; 2.5, 48, and 55 for FGF-2; 19, 112, and 66 for IGFR2; 140, 45, and 52 for BMP4. There were significant differences in NGF-2 immunoreactivity between groups I and III (P = 0.0023) and in BMP4 immunoreactivity between groups I and II (P = 0.017) and groups I and III (P = 0.022). All MCs expressed high levels of membranous beta-catenin, moderate levels of TGF beta 3 and IGFR2, and low levels of FGF-2, with no significant differences seen among the groups. MCs with prominent MS and MA (group I) expressed significantly higher BMP4 than those in groups II and III, suggesting a potential role of BMP4 in the pathogenesis of MA. The level of NGF-2 expression was significantly lower in group I than in group III, possibly indicating abnormal angiogenesis in the formation of angiopathy.

Metaplastic mammary carcinoma with osteoclast-like giant cells is a rare neoplasm, and the histogenesis of this tumor remains controversial. A case of metaplastic mammary carcinoma with osteoclast-like giant cells in a 72-year-old woman is reported with p53 mutational analysis. Microscopically, the tumor was composed of a dominant sarcomatous stromal component containing osteoclast-like giant cells and a minor component of intraductal carcinoma. Immunostaining for p53 revealed strong positivity in both intraductal and sarcomatous components, but not in osteoclast-like giant cells. Mutational analysis of the p53 gene disclosed an identical point mutation in both intraductal and sarcomatous components, but not in osteoclast-like giant cells, indicating that both components share the same progenitor cells, and osteoclast-like giant cells represent a reactive infiltrate.

The purpose of this study was to evaluate cyclooxygenase (COX)-2 expression in adenocarcinomas of the uterine cervix and its correlation with clinicopathologic features, angiogenesis, and tumor growth.Thirty-nine cases of FIGO clinical stage I and II adenocarcinoma of the uterine cervix were examined by immunohistochemical studies with anti-COX-2. Microvessels were immunohistochemically labeled with an antibody to CD34. Computerized image analysis was used to evaluate microvessel density (MVD). The apoptotic cells were visualized by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) and proliferative cells were visualized by staining with Ki-67 antibody.Twenty-eight tumors (71.8%) were classified as COX-2 positive. COX-2 expression correlated with FIGO stage (P0.01). Tumors expressing COX-2 had a significantly higher MVD and Ki-67 index than those that did not express COX-2 (P0.05). However, COX-2 expression did not correlate with the apoptotic index. In univariate long-rank analysis, COX-2 expression, MVD, and FIGO stage were associated with shortened survival. However, FIGO stage and MVD were the only independent prognostic factors by multivariate analysis.Our results suggest that COX-2 expression in cervical adenocarcinomas may contribute to tumor progression by increasing angiogenesis and cell proliferation.

A slowly growing tumor in the right shoulder of a 38-year-old white male, which felt like a superficial cystic mass, was studied. The spindle cells, which represented the main component of the tumor, were arranged in a typical storiform pattern and were positive for CD34 and focally for CD117. The pigmented cells were mostly found at the center of the storiform whorls and were negative for S-100 protein and HMB-45. Ultrastructurally, the tumor consisted predominantly of nondescript mesenchymal spindle cells that resembled fibroblasts. The tumor cells blended into a loosely arranged stromal tissue background. The general appearance of pigmented cells was very similar to the nonpigmented spindle cells. The pigment appeared to be a mature form of melanin granules. The lack of premelanosomes, cell injections, basal lamina, and pinocytotic vesicles was inconsistent with a neural origin/neural differentiation hypothesis for this tumor.

The stem cell kinase CD117 has recently been found to play an important role in the development of interstitial cells of Cajal (ICC), which are currently regarded as pacemaker cells of the gastrointestinal tract. CD117 is expressed in both gastrointestinal stromal tumors (GIST) and ICC, with the latter regarded by many as the progenitor cells of GIST. The authors investigated immunoreactivity of 25 normal surgically removed small intestinal tissues and correlated the findings with electron microscopy (EM) on 12 cases. In all cases CD117-positive cells were frequently seen around the myenteric plexi either singly or in groups. CD117-positive cells on immunostained sections corresponded to the cells appearing as fibroblast-like or undifferentiated primitive mesenchymal cells around the myenteric ganglia and interstitial spaces by EM. In contrast, S-100 stain revealed a fine network of positive staining throughout the muscularis. Branches of nonmyelinated axons and nerve endings were found regularly between myocytes with direct contact with muscle cells by EM. The cells that we could depict as ICC because of their distribution and staining pattern of CD117 were limited to the nonmuscular mesenchymal cells. No muscle cell-like ICC were found. Instead, the muscle cells in direct contact with nerve endings were often disfigured and the cytoarchitectural contents for muscle cells became less distinct because of lighter staining and loss of definite focal densities among actin filaments. However, these latter cells did maintain most muscle cell features, such as continuous external lamina, caveolae, and some of the peripheral densities. These findings raise a possibility that previous investigators could have included these altered muscle cells into the ICC group. It was also found that intestinal muscularis not only was richly endowed with an elaborate neural network of delicate axonal extensions and dense-core granule containing nerve endings traversing through and between myocytes, but also showed frequent synapse-like direct contact between nerve endings and muscle cells. These findings indicate that enteric nerves may play a major role in the control of intestinal motility, while CD117-positive cells play an accessory role as cells of Cajal as originally speculated. Further studies are necessary to better define and characterize interstitial cells of Cajal, which will be useful in the correlation of the vast number of data concerning the possible role of CD117-positive ICC in the pacemaker function of the intestine and oncogenesis of GIST.

Two cases of an oncocytic adrenal cortical tumor that contained peculiar cytoplasmic crystalline inclusions in the tumor cells are presented. The patients were 49- and 72-year-old females without clinical and biochemical evidence of adrenal cortical or medullary dysfunction. The adrenal tumors weighed 80 and 200 g each. These crystalline inclusions were present in groups of longitudinal profiles or clusters of crossly cut aggregates. They appeared in clusters of membrane-bound columns. On longitudinal sections, they appeared as rigid rods of homogenous density measuring 36 nm in width, but when they were cut transversely their paracrystalline nature became apparent. They were composed of closely packed microtubules in rectangular blocks. The microtubules measured 12.5 nm with a hollow center measuring 4.2 nm. The inclusions were within the membrane-bound cisterna of rough-surfaced endoplasmic reticulum. The significance of these inclusions is not clearly understood; however, they have been seen only in adrenal cortical tumors and their presence may be helpful in the differential diagnosis of adrenal oncocytic tumors. One patient presented with a tumor in which gross and microscopic appearance was compatible with a pheochromocytoma. This case exhibited an oncocytic appearance and pronounced cellular pleomorphism. Ultrastructural studies were necessary to recognize the tumor cells as cortical cells. The tumor cells contained abundant mitochondria with tubular cristae, paranuclear parallel stacks of granular endoplasmic reticulum, and relatively prominent smooth endoplasmic reticulum. These features are typical of adrenocortical cells. In addition, frequent tumor cells contained the peculiar cytoplasmic inclusions herein described.

Five cases of spindle cell carcinoids of the lung were analyzed by immunohistochemical and ultrastructural technique. They were found to be biphasic tumors composed of the major component of neuroendocrine cells (chief cells) and a minor component of dendritic cells (supporting cells). The chief cells displayed positivity for neuroendocrine phenotypic antigenic markers: neuron specific enolase (NSE), chromogranin A, and synaptophysin. They contained varying numbers of dense-core granules by electron microscopy. In addition, the chief cells expressed cytoplasmic positivity for cytokeratins. The supporting cells were dendritic in appearance and displayed strong positivity for S-100 protein in all cases. Glial fibrillary acidic protein was positive in two cases. On electron microscopy, the supporting cells were agranular and found along the external lamina surrounding the nests of tumor cells. In two cases, rare ganglion cell-like cells were present. The histomorphologic, immunohistochemical, and ultrastructural features were contrastingly different from the classical pulmonary carcinoid and rather resembled gangliocytic paragangliomas arising from small intestine and spine. It is proposed that pulmonary carcinoids with biphasic features are better designated as gangliocytic paragangliomas of the lung rather than paraganglioid carcinoids.

Polypoid endobronchial lesions occurred in a patient with acquired immunodeficiency syndrome (AIDS) with recent fever, skin lesions, lymphadenopathy, lung infiltrates, and pleural effusions. His condition improved with antimicrobials and vincristine. After therapy ceased, skin lesions recurred and gastroesophageal mucosal lesions developed. Bacillary angiomatosis was identified during retrospective analysis of skin and endobronchial biopsy specimens.

A 56-year-old white woman, seropositive for human immunodeficiency virus for 18 months without signs of acquired immunodeficiency syndrome, presented with retrosternal pain and progressive dysphagia secondary to an exophytic esophageal mass. Biopsies of the tumor showed a malignant neoplasm composed of pleomorphic, noncohesive cells growing in a diffuse, sheet-like fashion. Immunohistochemically, tumor cells were nonreactive with epithelial, lymphoid, neural, and monocyte/macrophage markers. Despite the noncontributory immunohistochemical findings, ultrastructural study of the tumor cells revealed convincing histiocytic features. Individual cells possessed long, slender filopodial projections, prominent Golgi apparatus, residual bodies, rare lysosomes, and prelysosomes. Immunoglobulin heavy chain and T-cell receptor gamma gene rearrangement studies detected no evidence of a clonal gene rearrangement. The patient responded poorly to chemotherapy and died 5 months after her initial symptom of dysphagia.

Diffuse renal involvement by numerous oncocytic nodules has rarely been described. We report 14 cases (19 specimens) with innumerable oncocytic nodules in the kidney. Invariably, these kidneys showed additional associated findings. We suggest the term renal oncocytosis for this entire morphologic spectrum. Six (43%) cases had histologically or radiologically proven bilateral involvement. Each specimen had at least one dominant tumor (2.0-10.5 cm) in addition to numerous other microscopic to macroscopic oncocytic nodules. Additional features observed were: interstitial pattern, with the oncocytic tubules and acini diffusely intermingling with and infiltrating between non-neoplastic parenchyma (one case); diffuse oncocytic change in the nonneoplastic tubules, cytologically difficult to separate from the oncocytic nodules (seven cases); and benign oncocytic cortical cysts (four cases). The dominant mass in 13 specimens was a renal oncocytoma and in two, a chromophobe renal cell carcinoma. In four specimens, the largest tumor was considered a hybrid tumor because of the presence of mixed histologic features of both tumor types. Most smaller nodules had the morphologic features of renal oncocytoma, but a few had the appearance of chromophobe renal cell carcinoma or nodules with hybrid features. We conclude that the presence of numerous oncocytic nodules may be associated with a wide spectrum of oncocytic changes in the kidney. The association of numerous renal oncocytoma-like nodules with lesions having a mixed morphology or a morphology of pure chromophobe renal cell carcinoma suggests that they may constitute a morphologic spectrum of oncocytic tumors and that renal oncocytoma and chromophobe renal cell carcinoma may arise from a common progenitor lesion.

Unlike smooth muscle elsewhere in the body, the smooth muscle of the iris and ciliary body is derived from neuroectoderm (mesectoderm). Leiomyomas that arise from the ciliary body, and therefore are of mesectodermal origin, may resemble spindle cell neurogenic tumors by light microscopy. They show positive immunostaining for smooth muscle actin but negative staining for neural markers. Ultrastructurally, the cells have the features of smooth muscle cells. The authors report a typical case of mesectodermal leiomyoma in a 47-year-old woman in which skeinoid fibers, considered to be an ultrastructural marker of neurogenic spindle cell tumors, were frequent together with other ultrastructural features often seen in neuroglial cell tumors. The findings indicate that mesectodermal leiomyoma is unique in its histogenesis as well as in its morphology.