Search

Copyright of Turkish Journal of Pathology is the property of Turkish Journal of Pathology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, KIT and PDGFRA gene mutations which play a crucial role in biologic behavior and treatment of gastrointestinal stromal tumors that is the most commonly seen mesenchymal tumors in the gastrointestinal system were evaluated in a series of 29 cases. Total genomic DNA extracted from the paraffin embedded tumor tissues of 29 cases were used as template DNA. With designed primers for exons of KIT and PDGFRA genes, target DNA was amplified using optimized PCR techniques. Amplicons were screened for mutation. After screening, the exons suspected of having undergone mutation were subjected to DNA sequencing analysis. In 17 cases, quality and amount of extracted DNA obtained from archival blocks were sufficient. In only 11 cases, all targeted exons could have been amplified efficiently for further applications and mutations were observed in 4 of these 11 patients. In conclusion, we suggest that it would be reasonable to provide screening tests for mutation in exons 9, 11, 13, 17 for KIT gene and exons 12, 14, 18 for PDGFRA gene following the establishment of the diagnosis of GIST. [ABSTRACT FROM AUTHOR]

Discusses the composition of Schwannomas as common benign tumors and differentiated neoplastic Schwann cell. Identification of the mature adipose and hematopoetic elements that resemble bone marrow; Performance of the ultrasonic imaging and computed tomography scanning; Mixture of spindle cell tumor and myelolipoma characterized by mature adipocytes and hematopoetic cells.

Background: Infantile myofibromatosis is a proliferative disorder of infancy and early childhood characterized by the development of single or multiple nodular lesions arising from cutaneous or subcutaneous tissue, muscle, bone or visceral organs. In approximately one-third of cases, this myofibroblastic proliferation involves the head and neck region. Case report: In this paper we report on three cases of cranial infantile myofibromatosis in infants. The clinical presentation and the deceptive histopathological features can make diagnosis difficult. Conclusion: The significance of recognizing this entity is stressed, since its indolent clinical behavior might prevent diagnosis. [ABSTRACT FROM AUTHOR]

The RET finger protein (RFP), which belongs to the B box zinc finger protein family, has a tripartite motif consisting of a Ring finger, a B box finger and a coiled-coil domain. The RET finger protein becomes oncogenic when its tripartite motif is fused with the tyrosine kinase domain of the RET protein. This study examined the RFP expression in normal and tumor tissues by immunohistochemistry. RFP was detected in the nuclei of various cells, including peripheral and central neurones, hepatocytes, adrenal chromaffin cells and male germ cells. Among them, RFP was expressed at high levels in male germ cells such as primary spermatocytes and round spermatids, and formed a perinuclear cap structure in primary spermatocytes. On the other hand, high levels of cytoplasmic expression of RFP were observed in some plasma cells as well as solitary plasmacytoma and multiple myeloma. These results suggested that different nuclear/cytoplasmic distributions of RFP might play a role in the regulation of growth or differentiation of different cell types. [ABSTRACT FROM AUTHOR]

Presents the case of a 31-year old woman with a single nodule in the right thyroid lobe. Medical history of the patient; Result of the gross examination of the thyroidectomy specimen of the patient; Information on papillary thyroid carcinoma, a common malignant tumor of the thyroid.

Presents a case study on a 6-year old girl with diabetes insipidus and lytic lesions in the skull. Clinical history of the patient; Pathologic diagnosis on the case; Characteristics of histiocytic syndromes.

Objective: The pilomatrixoma is a relatively rare skin neoplasm. It is a benign disease, originating from hair follicle matrix cells and, it represents 0,12% of all skin tumors. It is mostly located in head and neck particularly in the preauricular region. Clinically it presents as a slow growing, well-circumscribed subcutaneous or intracutaneous mass with hard consistency. Although the diagnosis of pilomatrixoma can be made on the basis of clinical features, the definitive diagnosis is made on histopathological examination. This tumor may be misdiagnosed and unnecessarily treated by aggressive resection by the physicians. Case Report: A 6-year old female presented with a preauricular subcutaneous mass and she underwent excision of the mass. Histopathological examination of the excised mass revealed pilomatrixoma. The postoperative period was uneventful and there were no signs of recurrence with one year of follow-up. Conclusion: In the presented paper, the features of pilomatrixoma were discussed in the light of the recent literature. Physicians should consider pilomatrixoma in the differential diagnosis of the superficial preauricular masses to avoid unnecessary wide excisions. [ABSTRACT FROM AUTHOR]

In metastatic melanoma, the detection of somatic mutations in the BRAF gene is crucial regarding patient selection for targeted therapy. Several screening methods have been developed to identify BRAF gene mutations. In this study, our objective was to evaluate the detection of the BRAF V600 mutations using two molecular methods, real-time polymerase chain (real-time PCR) assay and pyrosequencing, and immunohistochemistry (IHC), and to compare the results of these different technical platforms. This study included 98 patients diagnosed with metastatic melanoma at the Hacettepe University, Department of Pathology between 2002 and 2014. BRAF mutation analysis was tested with real-time PCR, pyrosequencing and IHC methods. The results of all three tests were compared with a reference test, and the sensitivity, specificity rates and kappa coefficient values were analysed for each test. We successfully analysed BRAF mutations using all three methods in 92 patients. According to our findings, the pyrosequencing method had the highest kappa value regarding the determination of BRAF V600 mutations. The kappa values were at almost perfect agreement levels in pyrosequencing and real-time PCR assay (kappa coefficient for pyrosequencing=0.895 (95% CI: 0.795-0.995); kappa coefficient for real-time PCR=0.871 (95% CI: 0.761-0.981). The kappa value was at a substantial agreement level in the IHC analysis (kappa coefficient=0.776 (95% CI: 0.629-0.923). According to our results, we found that real-time PCR and pyrosequencing methods were equally excellent in determination of BRAF V600 mutations. The IHC method, which is commonly used in routine pathology practice, can also be safely used as a screening test for determination of BRAF V600 mutations., (Copyright © 2017 Elsevier GmbH. All rights reserved.)

Objective: Programmed death ligand 1 (PD-L1) found on tumor cells has recently been reported to have a key role in the development and dissemination of many tumors, such as lung and breast carcinomas. In this study, we retrospectively analyzed PD-L1 expression among different types of sarcomas., Material and Method: Tissue microarrays of 3-4 mm diameter were composed from paraffin blocks of 222 various sarcomas. Slides prepared from microarrays were stained for PD-L1 antibody (Cell Signaling, E1L3N®) using Leica Bond Autostainer. Any membranous staining over 5% of the cells was regarded as positive. Quantitative real-time PCR with TaqMan gene expression assays for PDL1 was performed using whole sections from FFPE tissue of PD-L1 positive cases, by normalizing absolute values to β-actin. Relative expression level of mRNA of PDL1 was calculated and scored using Log102(threshold cycle of b-actin - threshold cycle of PDL1)., Results: Immunohistochemically, PD-L1 expression was present in 34 of 222 (15%) sarcomas. 5/13 (39%) undifferentiated pleomorphic sarcomas, 6/18 (33%) malignant peripheral nerve sheath tumors, 5/16 (31%) dedifferentiated liposarcomas, 4/19 (21%) rhabdomyosarcomas, 2/16 (13%) epithelioid sarcomas, 2/15 (13%) leiomyosarcomas, 3/26 (12%) synovial sarcomas, 1/18 (6%) myxoid liposarcoma, 1/2 (50%) extraskeletal myxoid chondrosarcoma, 1/3 (33%) alveolar soft part sarcoma, 1/3 (33%) parachordoma/myoepithelioma, 1/5 (20%) pleomorphic liposarcoma, 1/7 (14%) angiosarcoma, 1/8 (13%) Ewing sarcoma showed PD-L1 expression. Cases of solitary fibrous tumor/hemangiopericytoma (18), desmoplastic round cell tumor (14), Ewing-like sarcoma (6), epithelioid hemangioendothelioma (5), clear cell sarcoma (4), myxofibrosarcoma (4), low grade fibromyxoid sarcoma (2) were all negative. Tumor-infiltrating hematopoietic cells were positive for PD-L1 in 32 cases (15%) with only 2 cases overlapping with PD-L1 staining in tumoral cells. Sixteen of 34 (47%) immunohistochemically PD-L1 positive cases showed significant but low-level PD-L1 mRNA overexpression., Conclusion: We have shown PD-L1 expression in a subset of sarcomas, both at the protein and mRNA level. High-grade pleomorphic sarcomas tend to show more frequent PD-L1 expression. Clinical trials are necessary to further assess the effect of anti PD-L1 drugs on sarcomas showing PD-L1 expression.

Nasopharyngeal carcinoma (NPC) is associated with the Epstein-Barr virus (EBV). Human papilloma virus (HPV) has also been detected in NPC cases. In this retrospective study, we analyze the frequency of EBV and HPV infection in 82 Turkish patients with NPC. A total of 82 were evaluated for EBV and HPV. In situ hybridization (ISH) was performed for EBV. HPV-ISH and P16 immunohistochemistry used to determine the HPV status. Seventy-two of the 82 (87%) NPC patients were EBV-positive. The highest rate of EBV-positivity was found in undifferentiated NPC patients, which accounted for 65 of 68 (95.6%) undifferentiated cases. One of the 82 NPC patients whose tumor was non-keratinizing differentiated, contained HPV. Our data shows that EBV is closely associated with NPC in Turkey. We found lower rates of HPV-positivity in NPC patients than in North American populations. In addition, both EBV and HPV-negativity were more associated with decreased survival than EBV-positive cases., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

Aim: To determine the methylation pattern of the promoter region of the O6-methylguanine-DNA methyltransferase (MGMT) gene in laryngeal cancer and normal laryngeal mucosa samples using pyrosequencing, and to determine the relationship between the methylation pattern of MGMT, and tumor stage, survival, recurrence, and chemosensitivity in patients with laryngeal cancer., Materials and Methods: Laryngeal cancer and normal laryngeal mucosa specimens were obtained from our paraffin block archives, and then subjected to pyrosequencing. Different cut-off values were used to detect methylation. Clinicopathological data for the patients that provided specimens were obtained from archive records., Results: When 5% was used as the cut-off value, 78% of the laryngeal cancer specimens (64 of 82), and 27.3% of normal laryngeal mucosa specimens (3 of 11) were considered methylated. When 10% was used as the cut-off value, 47% of the laryngeal cancer specimens (39 of 82), and none of the normal laryngeal mucosa specimens were considered methylated. There was not a significant relationship between the methylation status of MGMT, and clinicopathological parameters, including age, tumor stage, histopathological differentiation, chemoradiotherapy protocol used, recurrence, or disease-free survival., Conclusion: Pyrosequencing is a reliable semiquantitative technique that can be used to detect the methylation pattern. Methylation was common in the laryngeal cancer specimens, but there was not a significant relationship between the methylation status of MGMT and clinicopathological parameters., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

Intra-abdominal hypertension and abdominal compartment syndrome (IAH/ACS) are life-threatening conditions and caused by several clinical status. Although there is insufficient data regarding its effects on adrenal glands. This study aimed to identify whether elevated intra-abdominal pressure (IAP) caused any alteration on the morphology and function of adrenal glands in a rat model. Twenty four Sprague-Dawley male rats were included in the study. Animals were allocated into 4 groups. IAP was elevated to 15 mmHg for one hour and four hours in group 2 and 4. Group 1 and 3 were sham groups. Blood samples were taken for the assessment of plasma adrenaline, noradrenaline, and corticosterone levels and adrenalectomies were performed to evaluate apoptosis. Blood adrenaline, noradrenaline and corticosterone levels were significantly higher in the study groups compared with the sham groups. However, there were no significant changes in apoptotic index scores in the study groups as compared to sham groups. These results support that increased IAH leads to discharge of catecholamine and corticosterone from the adrenal glands. Failure to demonstrate similar changes in apoptotic index score may be concluded as apoptosis is not a leading pathway for impairment of adrenal glands during IAH period.

Rapid growth in knowledge of cell and molecular biology led to the increased usage of molecular techniques in anatomical pathology. This is also due to the advances achieved in the techniques introduced in the last few years which are less laborious as compared to the techniques used at the beginning of the "molecular era". The initial assays were also very expensive and were not performed except for selected centers. Moreover, the clinicians were not sure how to make use of the accumulating molecular information. That situation has also changed and molecular techniques are being performed in a wide variety of medical settings which also has a reflection on the endocrine system pathology among other organ systems. This review will provide an update of genetic changes observed in different endocrine system pathologies and their diagnostic, therapeutic and prognostic values.

Objective: To determine the incidence of dysplasia as a preneoplastic change and high-risk human papilloma virus (HPV) infection in penile condylomas, which are common HPV-related lesions and considered a risk factor for penile cancer., Methods: Histologic analysis was done of 58 consecutive penile condylomas with tissue diagnosis. An immunohistochemical panel that included stains for p53, Ki-67, and p16INK4a was also used. HPV typing was successfully performed in 43 lesions. Genotyping was accomplished through polymerase chain reaction and flow-through hybridization with an HPV GenoArray Diagnostic Test kit., Results: Dysplasia was observed in 13 of the 58 condylomas (22%). High-risk HPV DNA was detected in 5 of 10 dysplastic lesions (50%) for which tissue blocks were available for study. High-risk HPV was not detected in the nondysplastic lesions (P<.001). Ki-67≥20% above the basal layer of epithelium and p53-positive immunostaining occurred more frequently in dysplastic lesions than in nondysplastic lesions; however, the difference was not statistically significance. Staining for p16INK4a was not helpful., Conclusion: Anogenital condylomas in men are usually treated using destructive methods or with medication. We suggest that at least a part of the lesion must be removed and sent for histopathologic examination. If the histologic result shows significant dysplastic alteration, the lesion should be further investigated to determine the subtype of infective virus, because 50% of such lesions are associated with high-risk HPV. When oncogenic pathogens are found, careful patient follow-up for recurrences and counseling for the patient and his sexual partner(s) may be warranted., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objective: Endometrial cancer is a common malignancy of the gynecological system and has been classified into two major groups, Types I and II. Type I tumors are estrogen-related, low-grade endometrioid tumors, whereas type II tumors are aggressive, high-grade non-endometrioid tumors. Ret finger protein is a nuclear transcription factor with a tripartite motif that is highly expressed in different tumor cells., Material and Method: To analyze the expression of ret finger protein in endometrial tissues and cancer, 18 cases of secretory and proliferative endometrium, endometrial polyp, endometrial hyperplasia and endometrial intraepithelial neoplasia and 21 cases of types I and II endometrial carcinoma were evaluated immunohistochemically., Results: Although rare cases of secretory endometrium showed a weak focal nuclear positivity, remaining proliferative endometrium, endometrial hyperplasia and type I endometrioid cancer cases were negative. In contrast, all cases of serous cancers showed strong nuclear positivity. After these strong positive results for serous endometrial cancer, 12 more cases of ovarian and endometrial serous carcinoma cases were added to the study. All of the additional cases were also strongly positive for ret finger protein., Conclusion: We suggest that ret finger protein might play a role in the carcinogenesis of the serous tumors of gynecological system and can be used to differentiate serous carcinomas from other epithelial tumors.

RET finger protein (RFP), which belongs to the large B-box RING finger protein family, has been reported to be expressed in breast carcinoma cell lines. We conducted this study to evaluate the expression level of RFP in breast carcinomas. Tissue microarrays were constructed from 133 cases of invasive breast carcinoma. Sections obtained from tissue arrays and whole sections from 10 non-neoplastic breast tissues were stained for ER, PR, ErbB2, and RFP using immunohistochemistry, and ErbB2 gene status was evaluated by FISH. The correlation between various immunohistochemical markers was determined. We found nuclear RFP expression in 41.4% of invasive carcinomas and in none of the non-neoplastic breast tissues. We also stained whole sections of 29 cases of invasive breast carcinoma, which included the TMA study, and 10 cases of ductal carcinoma in situ (DCIS) by RFP. We observed that four (40%) of the DCIS cases were positive with RFP. In statistical analysis, there was a significant, positive association between RFP and ErbB2 status at the protein level (p=0.002) and the gene level (p=0.049). There was no statistically significant association between the expression of RFP and tumor size, LN status, ER, PR, and grade (p>0.05). However, we found a significant association between age and RFP expression. RFP expression was stronger in patients 50 years or older (p=0.048). In our study, the expression of RFP correlated strongly with ErbB2 status. Our study is the first in the literature to show expression of RFP in patients with breast carcinoma. However, the possible role of RFP in breast carcinogenesis needs to be investigated in more detailed clinical and experimental studies.

Human Parvovirus B19 has previously been implicated in the pathogenesis of testicular germ cell tumors, but this could not have been confirmed. This study was designed to investigate the testicular persistence of Parvovirus B19 and possible associations with germ cell tumors. Paraffin-embedded or fresh tissues from 36 germ cell tumors, 20 germ cell aplasias, 26 normal testicular tissues, 20 liver tissues, and 20 spleen tissues were evaluated by two different molecular assays: a nested PCR for Parvovirus B19 capsid genes and a commercial quantitative real-time PCR. Positive results were further confirmed by another commercial real-time PCR assay. Viral DNA was detected in 3 of 36 (8.3%) germ cell tumors, but not in other groups. Viral loads observed in all positive samples were less than 20 IU/reaction, suggesting very low levels of viral replication or latency. These results either directly or indirectly imply the involvement of Parvovirus B19 with testicular germ cell tumors. Viral persistence in normal testis, germ cell aplasia tissues, or hepatic/splenic tissues was not observed in this study.

Objective: To investigate expression patterns and relationship of vascular endothelial growth factor (VEGF), vascular endothelial receptor-3 (VEGF-R3) (FLT-4) and cyclooxygenase-2 (COX-2) in psoriasis., Study Design: Forty-three patients were included in this study. The clinical severity of psoriasis was assessed using the psoriasis area and severity index (PASI). Punch biopsy samples both from psoriatic and nonlesional skin were taken and VEGF, VEGF-R3 and COX-2 expressions determined., Results: VEGF, VEGF-R3 and COX-2 expressions were detected in 90.9%, 78.0% and 86.4% of psoriatic and 84.1%, 71.8%, and 84.1% of nonlesional skin, respectively. Epidermal VEGF, VEGF-R3 and COX-2 expressions were detected in 56.8%, 77.8% and 34.1 of psoriatic and 75%, 78.1% and 65.9% of nonlesional skin, respectively. In dermis, VEGF, VEGF-R3 and COX-2 expression was observed in 88.6%, 77.5% and 84.1% of psoriatic and 81.8%, 64.1% and 77.3% of nonlesional skin, respectively. Among the PASI subgroups no statistically significant differences were detected for VEGF, VEGF-R3 and COX-2 expression., Conclusion: Our study demonstrated that VEGF, VEGF-R3 and COX-2 expression in psoriatic and nonlesional skin is significantly high in epidermis and dermis. Although there was significant concordance between VEGF and VEGF-R3 expressions in psoriatic lesions, there seems to be no concordance between the others.

Purpose: It was the aim of this study to assess the expression of vascular endothelial growth factor (VEGF)-A, matrix metalloproteinase (MMP)-9 and extravascular matrix patterns (EMPs) in iris and ciliary body melanomas and their correlations with histopathologic parameters., Methods: The study was conducted on 3 iris and 15 ciliary body melanomas. All tumors were subjected to immunohistochemical techniques for VEGF-A and MMP-9 expressions, the presence of EMPs was assessed, and routine paraffin sections were stained with hematoxylin-eosin. Cell type, tumor localization, degree of pigmentation, necrosis, mitotic index, lymphocytic infiltration and sclera invasion were analyzed using light microscopy., Results: The mean patient age at the time of treatment was 43 years (range 19-69, median 39.5); 10 (55.6%) patients were males and 8 (44.4%) females. Histopathological cell types were spindle cells in 55.6%, mixed cells in 16.7%, and epithelioid cell types in 27.8% of tumors. Positive reaction for VEGF-A and MMP-9 was present in 66.7 and 72.3% of the tumors, respectively. Microvascular loops and/or networks were seen in 33.4% of the tumors, with the remaining 66.7% of tumors displaying one or more of the other patterns. Metastatic disease developed in only 1 patient during follow-up. Tumor cell type, tumor size, mitotic rate, degree of pigmentation and EMPs were not correlated with metastasis., Conclusions: This study suggests that VEGF-A and MMP-9 were positive in the majority of iris and ciliary body melanomas. No correlation was found between VEGF-A and MMP-9 immunoreactivity and EMPs and occurrence of metastases in cases of anterior uveal melanoma.

Objective: Behçet's disease (BD) is an immunoin-flammatory vasculitis with an unknown etiopathogenesis. Vascular endothelial growth factor (VEGF) is a cytokine-stimulating angiogenesis. It has been suggested to play a role in inflammation and pathogenesis of vasculitic processes., Study Design: VEGF and CD34 expressions were assessed in samples taken from oral aphthous lesions. The patients were evaluated for disease activity, duration of lesions, serum C-reactive protein (CRP) levels and erythrocyte sedimentation rate (ESR)., Results: Twenty-six patients were included. Fourteen (53.9%) had increased CRP levels and 12 (46.1%) had increased ESR levels. Positive VEGF and CD34 staining were detected in 46.2% and 69.2% of biopsy samples, respectively. There was good positive correlation between them. The frequency of positive VEGF and CD34 staining was statistically higher in lesions with a duration of more than 6 days. No correlation was found between positive VEGF staining and serum CRP level, ESR and disease activity., Conclusion: Increased VEGF expression in correlation with CD34 positivity in oral aphthous lesions may show the role of VEGF in pathogenesis of these vasculitic lesions. We have concluded that VEGF may play a role during the course of oral aphthous lesions in BD.

Objective: In this study we hypothesized that if timing of gamma probe-guided parathyroidectomy were individualized according to an optimal-time-to-surgery technique, in vivo characterization of parathyroid lesions would be possible. We compared our findings with an ex vivo counting method ("20% rule") and frozen section results., Study Design and Settings: Thirty-five patients who were referred for surgical treatment of hyperparathyroidism were studied. Maximum parathyroid to thyroid sestamibi uptake ratio (UR(max)) was measured by use of preoperative dynamic scintigraphy. The interval between sestamibi injection and UR(max) was defined as the optimal time to surgery. On the day of surgery, the patients received the same dose of sestamibi and were taken to the operating room at UR(max) as determined by preoperative scintigraphy. Intraoperative in vivo gamma probe counts from parathyroid lesions were compared with in vivo contralateral background thyroid counts (in vivo/Bkg) and to ex vivo parathyroid counts relative to postexcision background of the adjacent normal tissue (ex vivo/Bkg)., Results: A total of 70 excised lesions were evaluated. In vivo/Bkg counts obtained from parathyroid adenoma were significantly different from parathyroid hyperplasia (z = -3.093, P = 0.002) and other lesions (z = -3.958, P = 0.0001). By receiver operating characteristic curve (ROC) analysis, we found the cutoff value for the in vivo/Bkg counts ratio to be 103% to differentiate parathyroid adenoma from hyperplasia with a sensitivity, specificity, and accuracy of 82.5, 65, and 74.4%, respectively. On the other hand, sensitivity, specificity, and accuracy of the ex vivo/Bkg method to differentiate parathyroid adenoma from hyperplasia with a cutoff value of 34.7 was found to be 70.8%, 60%, and 65.9%, respectively. The difference between the accuracy of these 2 tests was not significant statistically (P = 0.137). Sensitivity of frozen section to differentiate parathyroid adenoma and hyperplasia was 76.2% and 33.3%, respectively., Conclusions: Patient-specific optimal protocol for timing of sestamibi injection together with in vivo/Bkg method is a useful alternative method in guiding the surgeon to differentiate parathyroid adenoma from parathyroid hyperplasia and other tissues and may help surgeons' decisions during the operation. Combined use of in vivo/Bkg and ex vivo/Bkg methods may give more accurate results than frozen section.

Background/aims: Several studies have suggested that pancreatic exocrine cells are able to differentiate into endocrine cells. REG I has been shown to be crucial for induction of ductal epithelial cells to differentiate into insulin producing cells. To date, however, there has been no study which examined the expression of REG I along with other differentiation markers in patients with chronic pancreatitis., Methodology: Six cases with chronic pancreatitis and the pancreata from the age-matched autopsy cases of unrelated diseases (n=2) were included in this study and examined by immunostaining methods using antibodies against human REG I protein, trypsin, insulin, chromogranin A, cytokeratin 19 and Ki-67., Results: In chronic pancreatitis, REG I was found in acinar and acinoductular cells and the latter were also characterized by cytokeratin 19 positivity. The acinoductular cells showed the budding of REG I-positive cells which were also trypsin- and chromogranin A-positive. MIB-1 antibody against Ki-67 was found negative in the ductal, acinoductular and islet cells reflecting low proliferation in these cells., Conclusions: The current study revealed that acinoductular cells characterized by dual expression of REG I and cytokeratin 19 also express insulin, chromogranin A and trypsin and therefore supports the hypothesis that transdifferentiation of fully differentiated (acinar) cells may be the main source of islet neogenesis in patients with chronic pancreatitis. However, low proliferation rate in these cells limits the regeneration capacity of the pancreatic tissue in these cases. The present results of double staining of REG I with cytokeratin 19, chromogranin A and insulin in the acinoductular cells indicate that REG I may be used as a marker for these cells.

The use of neuronal nuclear antigen (NeuN) as a reliable neuronal marker in the differential diagnosis of clear cell neoplasms of the central nervous system was determined in a biopsy series of 23 cases. Immunohistochemical analyses were carried out by antisera against neuronal nuclear antigen, synaptophysin, neuron-specific enolase, microtubule-associated protein 2, and glial fibrillary acidic protein. All eight central neurocytomas were characteristically immunolabeled by NeuN. NeuN immunoreactivity was uniformly strong and basically located in the nuclei of neurocytes. Despite this uniform staining pattern of central neurocytomas, 12 cases of oligodendrogliomas and three cases of ependymoma were negative for NeuN. As the diagnostic criteria for central neurocytoma include immunohistochemical and/or ultrastructural evidence for neuronal differentiation, NeuN as a sensitive and specific neuronal marker in formalin-fixed, paraffin-embedded tissues may greatly facilitate the differential diagnosis of central neurocytomas.