The distinction between epithelioid mesothelioma and lung adenocarcinoma remains an important diagnostic challenge for surgical pathologists. The aim of the present study was to select a limited and appropriate panel of antibodies that can differentiate between epithelioid mesothelioma and lung adenocarcinoma. Specimens of 90 epithelioid mesotheliomas and 51 lung adenocarcinomas obtained from Japanese cases were examined using calretinin, WT1, AE1/AE3, CAM5.2, cytokeratin (CK) 5/6, vimentin, epithelial membrane antigen (EMA), thrombomodulin, CEA, CA19-9, and CA125. Ninety-six percent of epithelioid mesotheliomas were positive for calretinin; 99% for WT1; 100% for AE1/AE; 97% for CAM5.2; 70% for CK 5/6; 91% for vimentin; 96% for EMA; 71% for thrombomodulin; 77% for mesothelin; 7% for CEA; 17% for CA19-9; and 85% for CA125. In contrast, 33% of lung adenocarcinomas were positive for calretinin; 16% for WT1; 100% for AE1/AE3, CAM5.2, and EMA; 41% for CK 5/6; 47% for vimentin; 20% for thrombomodulin; 69% for mesothelin; 98% for CEA; 73% for CA19-9; and 80% for CA125. For distinguishing between epithelioid mesothelioma and lung adenocarcinoma, the combination of CEA, calretinin and each WT1 or thrombomodulin was suggested to be the best panel of immunohistochemical markers.

Differentiation of sarcomatoid mesothelioma from other sarcomatoid tumors involving the pleura and other structures by light microscopy remains an important diagnostic challenge for surgical pathologists. The purpose of the present study was to investigate the utility of diagnostic immunohistochemistry for differentiating sarcomatoid mesothelioma from its histological mimics: true sarcoma and pulmonary sarcomatoid carcinoma. A total of 39 specimens of mesotheliomas with sarcomatoid components, 43 specimens of true sarcomas, and nine specimens of pulmonary sarcomatoid carcinomas were obtained from Japanese patients and examined using a 10-antibody panel (calretinin, WT1, AE1/AE3, CAM5.2, epithelial membrane antigen, desmin, a-smooth muscle actin, S-100 protein, CD34, and CD68). CAM5.2 had the highest sensitivity and specificity for differentiating sarcomatoid mesothelioma from true sarcoma. The combination of CAM5.2, WT1, and AE1/AE3 is recommended for routine pathological diagnosis. Accurate clinical information is necessary for differentiating sarcomatoid mesothelioma from sarcomatoid carcinoma.

Abstract. The objective of the present study was to present 4 recently encountered ovarian large-cell neuroendocrine carcinoma (LCNEC) cases, and to evaluate their clinicopathological features in the context of the previously reported 29 LCNEC cases. First, we described the clinical features of 4 recently encountered cases. Routine H&E staining and immunohistochemistry for CD56, synaptophysin and chromogranin A were performed on sections of both the LCNEC and epithelial carcinoma components. Clinical data for the total of 33 LCNEC cases were summarized, and the Kaplan-Meier survival curve was estimated. Our cases were observed in women aged 42-81 years. One case is clinically classified as FIGO stage IV with multiple metastases, and the others are classified as FIGO stages Ic, IIc and IIIb by post-surgical findings. Pathological features, assessed by H&E staining, were similar to lung LCNEC, and at least one neuroendocrine marker was positive staining in both LCNEC and the epithelial component. One case was pure type LCNEC and the others were mixed carcinoma. Paclitaxel/carboplatin chemotherapy was performed for all cases and 3 of the 4 treatments were effective. The prognoses of our cases were as follows: 1 in stage Ic died from the disease after only 2 months, but the others survived, with or without recurrence, for 32-64 months, whereas the total 5-year survival of the 33 LCNEC cases was 34.9%. In summary, our 3 LCNEC cases revealed ordinary chemo-sensitivity, resulting in a better prognosis than those previously described, apart from 1 case which exhibited aggressive behavior. For the future, a retrospective survey to elucidate the prognostic factors and prospective clinical studies to evaluate the efficacy of treatment modalities of ovarian LCNEC are necessary, particularly for aggressive LCNEC cases. IntroductionThe World Health Organization (WHO) defines large-cell neuroendocrine carcinoma (LCNEC) as a tumor with a large nucleus and a tendency to have neuroendocrine differentiation, and it defines ovarian LCNECs as miscellaneous tumors (1). In Japan, the term LCNEC was described for the first time in The General Rules for Clinical and Pathological Management of Ovarian Tumors by the Japan Society of Obstetrics and Gynecology and the Japanese Society of Pathology in December 2009. Until these classifications were established, LCNEC had been classified as anaplastic or poorly differentiated carcinoma and was synonymous with undifferentiated carcinoma of the non-small cell neuroendocrine type (1,2). According to the WHO classification of lung cancer (3), the pathological structures by H&E staining reveal a characteristic organization, such as round nest and sheet-like formation with frequently central coagulative necrosis, and rosette-like formation of tumor cells is often observed everywhere. The nucleus is large with granular or coarse chromatin, a prominent nucleolus and moderate or abundant cytoplasm. Additionally, neuroendocrine differentiation by immunohistochemical analysis, such as chromogranin A, sy...

Classic Hodgkin lymphoma (CHL) is a lymphoid neoplasia characterized by the presence of large tumor cells, referred to as Hodgkin and Reed-Sternberg (HRS) cells, originating from B-cells in an inflammatory background. As the clinical significance of B-cell markers has yet to be fully elucidated, this study aimed to clarify the clinicopathological significance of CD79a in 55 patients with CHL. They were immunohistochemically divided into two groups, comprising of 20 CD79a-positive and 35 CD79a-negative patients. There was no significant correlation between CD79a and CD20 expression ( r s = 0.125, P = 0.362). CD79a-positive patients were significantly older at onset ( P = 0.011). There was no significant correlation between CD79a-positivity and clinical stage ( P = 0.203), mediastinal involvement ( P = 0.399), extranodal involvement ( P = 0.749), or laboratory findings, including serum levels of lactate dehydrogenase ( P = 1) and soluble interleukin-2 receptor ( P = 0.251). There were significant differences in overall survival (OS) ( P = 0.005) and progression-free survival (PFS) ( P = 0.007) between CD79a-positive and CD79a-negative patients (5-year OS: 64.6% and 90.5%; 5-year PFS: 44.0% and 76.6%, respectively). Five patients in whom the majority (> 80%) of HRS cells expressed CD79a consisted of 4 males and 1 female aged between 52 and 81 years; 4 of them were in a limited clinical stage. We concluded that CD79a-positive CHL may have unique clinicopathological features.