Utility of MOC-31 monoclonal antibody in differentiating metastatic adenocarcinoma cells and reactive mesothelial cells in effusion cytology

In effusion cytology, a clear distinction between reactive mesothelial cells and metastatic adenocarcinoma cells is sometimes challenging mainly due to similarities in the cytomorphological features. In such cases for definitive diagnosis, paraffin-embedded cell block examination and immunohistochemistry are helpful in making this distinction. MOC-31 is one of the proposed immunomarker for adenocarcinoma cells. We undertook to evaluate the role of MOC-31 as a marker for identifying adenocarcinoma cells in effusion specimen. A total of 185 paraffin-embedded cell blocks of effusion samples were identified, of these 111 cases were of metastatic adenocarcinoma. MOC-31 was positive in 101 of the 111 cases of metastatic adenocarcinoma. Minimal focal cytoplasmic staining was also seen in 7 of the 74 cases of reactive mesothelial cells, but these were taken negative as they did not show membrane positivity. The sensitivity and specificity of MOC-31 for metastatic adenocarcinoma cells were 92.5%, and 100% respectively, positive and negative predictive value (NPV) was 100% and 91.14%, respectively. MOC-31 can be used as a reliable marker in effusions for distinguishing metastatic adenocarcinoma from reactive mesothelial cases.

Diagnostic Utility of Caveolin-1 and MOC-31 in Distinguishing Chromophobe Renal Cell Carcinoma from Renal Oncocytoma

PURPOSE: Renal tumors consist of heterogeneous groups that frequently show complex and overlapping morphology, thus making it difficult to make a correct diagnosis. One of the most problematic differential diagnoses is to distinguish chromophobe renal cell carcinoma (RCC) from oncocytoma. These should be distinguished by differences in their behavior and clinical outcome. Our study was performed to identify whether caveolin-1 and MOC-31 are useful immunohistochemical markers for differentiating chromophobe RCC from oncocytoma. MATERIALS AND METHODS: We selected 23 chromophobe RCCs, 8 oncocytomas, and 25 clear cell RCCs and performed immunohistochemical staining for caveolin-1 and MOC-31. RESULTS: Caveolin-1 was positive in 20 (87%) of 23 chromophobe RCCs, 0 of 8 oncocytomas, and 21 (84%) of 25 clear cell RCCs. MOC-31 was positive in 22 (96%) of 23 chromophobe RCCs, 2 (25%) of 8 oncocytomas, and 14 (56%) of 25 clear cell RCCs. There was a statistically significant difference in the expression of caveolin-1 and MOC-31 between chromophobe RCC and oncocytoma (p<0.001). In addition, clear cell RCC was also significantly different from oncocytoma in the expression of caveolin-1 (p<0.001) and was significantly different from chromophobe RCC in the expression of MOC-31 (p<0.001). CONCLUSIONS: Caveolin-1 and MOC-31 can be useful markers in the differential diagnosis of chromophobe RCC, oncocytoma, and clear cell RCC.