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This work demonstrates differences between B lymphocytes and T lymphocytes as seen in the scanning electron microscope (SEM). Slides of routinely prepared benign and malignant lymphoid tissues were viewed in the SEM. The location of prominent populations of T lymphocytes and B lymphocytes was verified by immunocytochemical staining respectively with CD3 and CD20 antisera. Benign tissues, including infant thymus and adult hyperplastic lymph node, were compared with malignant lymphomas of T-cell and B-cell types. The SEM appearance of benign B and T lymphocytes is compared utilizing the backscattered electron (BSE) mode and secondary electron (SE) mode in adult hyperplastic lymph node and infant thymus, respectively. The BSE and SE modes reveal that the sectioned T-lymphocyte nucleus has a more complex configuration than that of the B lymphocyte. T lymphocytes appear more discrete and separated one from another, while B lymphocytes exhibit close cellular association to form a syncytial array. These features are noted also in malignant lymphomas of B-lymphocyte and T-lymphocyte types, respectively. The SEM can distinguish between B and T lymphocytes by studying the differences in nuclear and chiefly the cell to cell appearances. The syncytial configuration of B lymphocytes may reflect prominent expression of cell adhesion molecules, e.g., ICAM-1, as noted in the literature.

Objective: To determine whether the measured sizes of erythrocytes in both paraffin-embedded sections and air-dried blood smears differ from values published in standard texts., Study Design: Routinely prepared surgical pathology slides as well as an air-dried blood smear were viewed with a scanning electron microscope. Erythrocytes were measured using the instrument software., Results: Erythrocyte size in the peripheral blood smear correlated well with textbook values, 7.2-7.9 microns. However, red blood cells within sectioned material from several laboratories showed a prominent decrease, ranging from 25% to 35%, as compared to textbook values, about 7 microns., Conclusion: Since cytologists and surgical pathologists often use the erythrocyte as a convenient marker on diagnostic slides, attention should be given to these observations in making sizing judgments.

The identification of microcalcifications in breast biopsy specimens is a common and important task for the surgical pathologist that may sometimes be problematic. Although visualized by preoperative mammographic and operative specimen radiography, some cases may fail to reveal calcifications by histopathologic examination or occasion laborious and time-consuming study to confirm sparse calcifications. The present study demonstrates how conventional bright-field and polariscopic light microscopy did require considerable effort to confirm rare calcification. On the other hand, scanning electron microscopy was employed directly on a routine slide and provided definitive visual and physical proof, e.g., by means of energy dispersive x-ray microanalysis of a rare calcification on a slide previously judged to be negative for calcium and in a short period of time. Recent instrument advances in high voltage beam stabilization and in the ability to vary the pressure of the scanning electron microscope in the vicinity of the specimen now allow complete insertion of a diagnostic glass slide with only trivial preparation. The report, although brief, raises important questions regarding the extent and prevalence of breast calcifications.

This unusual case is that of a middle-aged man exhibiting a tumor diathesis including a basal cell adenocarcinoma with features of adenoid cystic carcinoma arising in minor salivary gland of lip in association with multiple primary malignant cylindromas of skin. The labial lesion showed invasive tubules, solid epithelial sheets and cribriform structures. It did not exhibit PAS positive juxta-tubular basement membrane material. The skin lesions all showed features of a highly infiltrative cylindromatous carcinoma with two cell types, peripheral palisading and prominent PAS positive juxta-tubular basement membrane material. Immunocytochemical studies of the lip lesion and one of the skin lesions showed similarities, including positive staining for high and low molecular weight keratins and S-100 with negative staining for CEA. The precious descriptions of tumor diatheses involving dermal cylindromas and dermal analogue tumors of salivary glands and the distinctions with the present study are noted. If benign and even malignant cylindromas were described in the literature to be associated with basal cell adenocarcinoma of the major salivary glands, our case is unique by its association with this rare malignant tumor in a minor salivary gland.

A total of 15 cases of peripherally located lung carcinomas associated with scar (scar carcinoma) were studied by light microscopy and electron microscopy with energy-dispersive X-ray microanalysis (XMA). Results were compared to those of three autopsy lungs without significant pulmonary findings that served as controls. Fibrosis with scar formation characterized the 15 tumor cases. Particulate depositions including doubly refractile particles were also increased in the tumor group. XMA identified 25 elements with great complexity of particulate composition. Silicon was the most prominent element and was found in 16 of 18 cases studied. Kaolinite, feldspar, talc, muscovite, and silica were recognized. The fibrogenic properties of silicate compounds were emphasized, including their prominence in the lung tumor group. While the important concept of tumor desmoplasia was recognized, the study showed significant fibrosis in relation to fibrogenic materials, which undoubtedly preceded the appearance of the tumors. Also noted were the carcinogens uranium, cadmium, chromium, nickel, and arsenic, some of which were previously described as minor constituents of naturally occurring minerals.

We report a case of malignant granular cell tumor present in the left medial mid-thigh of a 69-year-old black male. The lesion was grossly fungating, partially ulcerated and measured 14 cm in largest diameter. Light microscopy, electron microscopy and immunohistochemistry techniques were used to confirm the preliminary cytologic diagnosis of malignant granular cell tumor. Diagnostic criteria of malignancy for such lesions are reviewed. Immunohistochemical and ultrastructural analyses support a neural or Schwann cell origin for the tumor. Clinical outcome for such lesions is discussed.

A 47-year-old woman had a lesion of the uterine cervix that presented clinically as a protruding or aborted leiomyoma. Grossly the tumor occupied a substantial portion of the cervical and endocervical region. Histologically it showed a spindle cell neoplasm arranged in large fascicles that penetrated deeply into the fibromuscular wall of the cervix. The tumor cells had abundant pink cytoplasm that contained considerable brown melanin granules confirmed by Fontana's stain. Cytologically nuclear pleomorphism, hyperchromatism, and giant nuclear forms were observed. Mitoses were also seen. Localized nuclear palisading was present. Electron microscopic examination of paraffin-embedded material revealed numerous premelanosomes and opaque granules that were compatible with mature melanosomes, thus confirming melanogenesis in the tumor. Tumor cells exhibited focal projections, and the connective tissue showed abnormal spacing of collagen. Basal lamina material was noted focally on tumor cell surfaces. Immunocytochemistry showed a positive reaction to S-100 protein and HMB-45 in tumor cell cytoplasm.

Activation of c-Ki-ras by point mutation within exon 1 was studied in 33 specimens of dysplastic gastrointestinal lesions or of cancers presumed to arise from dysplasia. Samples were obtained from patients with underlying ulcerative colitis or Barrett's esophagus, two diseases associated with dysplasia and increased rates of colonic or esophageal adenocarcinoma, respectively. Genomic DNA was amplified using primers bounding this exon in the polymerase chain reaction. Polymerase chain reaction products were analyzed by direct dideoxy sequencing. Three point mutations in codon 13 of c-Ki-ras were found, all in colonic specimens (two high-grade dysplasias and one adenocarcinoma arising in ulcerative colitis). No point mutations were observed in the second exon of c-Ki-ras or in and around codons 12, 13, and 61 of c-N-ras and C-Ha-ras in a partial sampling of the specimens. These data indicate that ras family protooncogene activation is an uncommon event at this level of malignant progression in these disease states. Carcinogenesis in ulcerative colitis and Barrett's esophagus may proceed via different pathways than in sporadic colon cancer, perhaps involving loss or inactivation of suppressor genes.

Pure leiomyoma of the breast, excluding the retroareolar lesion are rare. We are reporting here the 11th case described in the literature. They all appeared as benign, slow growing lesions without evidence of recurrence after complete surgical excision. The exact etiology still remains to be determined.

A 42-year-old female with clinical and endocrine indications of Cushing's syndrome, as well as periodic hypertension and increased urinary catecholamines and their metabolites, benefitted from removal of a pheochromocytoma. Adrenocortical hyperplasia was present. Electron microscopy showed catecholamine-type granules in the tumor cells; in addition, immunoreactive ACTH, leu-enkephalin, somatostatin, and serotonin were identified. Such studies were performed for the first time in this unusual condition.

Liver biopsies of white rates infected by Plasmodium berghei sporozoites were examined by electron microscopy. Intrahepatocytic schizont development was confirmed. In addition, at 60 and 70 h after sporozoite inoculation, exoerythrocytic merozoites were noted in Kupffer cells of liver sinusoids. Although it is theoretically possible that this observation may be of merozoite development in Kupffer cells, the authors suspect that this example of phagocytosis would be one of the host's natural defenses against sporozoite-transmitted malaria.

Ultrastructural and biochemical studies have suggested that bronchopulmonary carcinoids and oat cell carcinomas may be derivatives of neuroendocrine cells; their amine and/or peptide secretory capabilities may at times be reflected in clinical hormonal syndromes. This investigation was prompted by the hypothesis that dysplastic neuroendocrine bronchial cells may also exhibit structural and functional aberrations of their secretory apparatus. Surgical specimen samples from 5 human dysplastic bronchi were studied ultrastructurally; 7 normal bronchi served as controls. Golgi complexes of dysplastic cells were distinctly less prominent than those of the controls. Moreover, the Golgi vesicles of dysplastic cells appeared significantly smaller than their counterparts in normal cells (P less than 0.01). Also, dysplastic neuroendocrine cells displayed significantly fewer secretory granules per cell than the controls (P less than 0.05). These findings indicate structural abnormalities in the secretory apparatus of neuroendocrine cells in dysplastic bronchi and correlate with experimental observations of aberrant hormonal production associated with bronchial dysplasia. Thus, the possibility arises that bronchial epithelial dysplasias may be detected and monitored through laboratory determinations of their secretory products.

To identify the unknown liver cell type initially invaded by sporozoites of mammalian malaria, young rats were inoculated intravenously with large numbers of Plasmodium berghei sporozoites obtained from infected Anopheles stephensi mosquitoes. Fine structural studies of liver specimens obtained from the rats within 2 min after inoculation demonstrated the presence of morphologically unaltered sporozoites in the cytoplasm of hepatocytes. Many sporozoites were also observed undergoing cytolysis within the lysophagosomes of Kupffer cells, as well as other phagocytic cells. These observations strongly suggest direct infection of the hepatocyte by the sporozoite.

A patient had extensive foreign-body granulomatous inflammation of multiple skin sites and of the inguinal lymph nodes with splenomegaly, cutaneous anergy to common skin antigens, and peripheral blood eosinophilia. The patient had an elevated serum angiotensin-converting enzyme level. Histologically, the granulomas were of the foreign-body type with lymphocytes, histiocytes, eosinophils, and giant cells, some that contained doubly refractile crystalline material. Electron-probe x-ray microanalysis identified silicon, magnesium, iron, calcium, phosphorus, zinc, titanium, and chromium in the crystalline material. These findings suggest talc, cement, and inorganic pigment as possible sources of the crystals. This case is reported for its unusual clinical, laboratory, and morphologic features.

Meningiomas rarely arise from or remain limited to the temporal bone. When the diagnosis of temporal bone meningioma is made, it is mandatory to investigate the possibility of an intracranial component. Computerized axial tomography with contrast enhancement is of limited value in detecting small tumors adjacent to the temporal bone or within the internal auditory canal. If the computerized tomogram is normal, a positive contrast posterior fossa myelogram is indicated. The pitfall of depending solely upon computerized tomography to detect intracranial extension became clear in the evaluation of a patient found to have an unusual trilobed meningioma.

A case report is presented of a traumatized vascular hamartoma producing a forearm flexor compartment syndrome; such a case has not been reported previously. The role of minor trauma in this case was important. There is a need for a high degree of suspicion in order to make an early, accurate diagnosis. Delayed surgical decompression and resection of the pathologic muscle resulted in a dramatic improvement in sensibility and digital mobility.

Eleven endometrial adenoacenthomas were studied ultrastructurally. Special emphasis was placed on patterns of squamous metaplasia and the appearance of the basal laminae. Tonofibrils, irregular keratohyaline, abundant desmosomes, and foci of frank keratinization were observed. However, the granule population was small, with relatively scanty keratohyaline and no definite membrane coating granules. These features resemble squamous metaplasia observed in various epithelia; experimental models utilizing estrogens also resulted in similar changes. This observation appears pertinent in view of the possible etiologic role played by high estrogen levels in the development of human endometrial carcinoma. Most tumor cell clusters were surrounded by a well-defined basal lamina; focal basal lamina reduplication was also observed. These observations suggest a high level of differentiation in respect to synthetic capabilities and cell surface recognition. They correlate well with the relatively favorable prognosis generally observed in endometrial adenoacanthomas. However, these conclusions are tempered by the finding of occasionally absent or defective basal lamine, indicative of partial dedifferentiation of some neoplastic cells.

Focal crypt epithelial cell degeneration (apoptosis) of the rectum is a characteristic pathologic feature in AIDS. The presence of apoptosis usually implies cell-mediated cytolysis, which would be an unexpected finding in this disease. We investigated the ultrastructural features of apoptosis in rectal biopsies from five AIDS patients (three homosexual males and two females with i.v. drug abuse), three heterosexual controls, and two homosexual male controls. Apoptosis was found in all AIDS patients and, to a lesser extent, in one heterosexual control. Ultrastructurally, vacuolization of several adjacent cells, leading to extrusion of cellular debris through the basal lamina and phagocytosis by macrophages, was seen. No intracellular or extracellular viral particles were detected in the regions containing apoptotic bodies, in epithelial cells near the crypt bases, in intraepithelial lymphocytes, or in macrophages. In summary, apoptosis in the rectal crypts of patients with AIDS has the same ultrastructural features as in other conditions, which suggests that its pathogenesis is related to immune rather than infectious factors. If this process occurs on a chronic basis in multiple cell types, it would promote general tissue depletion, which has been demonstrated to occur in AIDS. The presence of apoptosis in AIDS is not explained by current concepts of disease pathogenesis.

A pulmonary neoplasm, evident initially as a metastatic nonpruritic skin rash in a 51-year-old man, progressed during a period of four months, leading to the patient's death. Histologic and histochemical studies of the skin metastasis, which were confirmed by transbronchial biopsy, demonstrated an adenocarcinoid tumor. Further ultrastructural studies of the skin metastasis showed that many tumor cells contained neurosecretory granules, although histochemical analyses had revealed the presence of only a few such tumor cells. Furthermore, in some cells both mucin and neurosecretory granules were present in the cytoplasm, confirming a previous observation in normal human segmental bronchi. These findings support the endodermal origin of such neoplasms.

A 22-year-old athlete, who had had intravenous injections of narcotics in the past, developed a viral hepatitis with markedly altered liver enzyme values. Studies revealed evidence of a virtual cure of hepatitis B virus and a current infection with delta agent. Liver biopsy showed a mixed-cell portal inflammation and doubly refractile crystalline particles. These particles were shown by energy-dispersive x-ray microanalysis to contain calcite, silica, talc, and a variety of elements including Al, P, S, Cl, K, Ti, Cr, Fe, Ni, Br, Yb, Os, Ir, and a trace U. The predominance of Ca-containing compounds suggested that the foreign material was present as a result of the chemical preparation of the narcotic or as a narcotic diluent. The potential for pathologic alteration by the various substances is discussed. These observations support the idea of particulate-induced hepatic disease advanced previously by others.

Sporoblast and sporozoite formation from oocysts of the avian malarial parasite, Plasmodium gallinaceum, after the seventh day of infection in Aedes aegypti mosquitoes offers an interesting example of differentiation involving the appearance and modification of several cellular components. Sporoblast formation is preceded by (a) invaginations of the oocyst capsule into the oocyst cytoplasm, (b) subcapsular vacuolization and cleft formation, (c) the appearance of small tufts of capsule material on the previously noted invaginations, and (d) linear dense areas located just below the oocyst plasma membrane which predetermine the site of emerging sporozoites from the sporoblast. The subcapsular clefts subdivide the once-solid oocyst into sporoblast peninsulae. Within the sporoblast, nuclei migrate from the random distribution seen in the solid oocyst and come to lie at the periphery of the sporoblast just below the linear dense areas noted in the earlier stage. A typical nuclear fiber apparatus occurs in most of the nuclei seen in random sections at this stage although such a fiber apparatus may occasionally be seen in the solid oocyst stage. The nucleus, its associated fiber apparatus, and the overlying dense area appear to induce the onset of sporozoite budding from the sporoblast as well as the formation of the sporozoite pellicular complex and the paired organelle precursor. Several mitochondria are present in each sporozoite, in contrast to the single mitochondrion seen in the merozoites of the erythrocytic and exoerythrocytic stages of avian malaria infection. The paired organelles and associated dense inclusion bodies are formed by condensation of an irregular meshwork of membrane-bound, coarse, dense material. The nature of small, particulate cytoplasmic inclusions is described.

Human endometrium taken during the early to mid-secretory portion of the menstrual cycle is studied with the electron microscope. A description of the nucleolus is given. In addition, an unusual structure within the endometrial cell nucleolus is described, consisting of amorphous matrix, 150-A dense granules, and a series of tubular channels. This structure is named the nucleolar channel system. A description is given of the geometric variability of the nucleolar channel system, its contents, and its relationship to the cytoplasm. The morphologic basis for a nucleolar-cytoplasmic interrelationship via the nucleolar channel system is described. Some of the implications of this relationship are discussed. The work of previous investigators on the nucleolar channel system is discussed.