EVALUATION OF A PANEL OF IHC MARKERS IN DIFFERENTIATION OF EXTRANODAL MALIGNANT SMALL ROUND CELL TUMORS

Background: The small round cell tumors are a heterogeneous group of malignant neoplasms. Immunohistochemistry (IHC) has proven to be a significant tool in the identification as well as differentiation of tumors which become a diagnostic challenge on the basis of routine haematoxylin and eosin (H & E) stain alone. The aim of present study was to study the histomorphological spectrum of extranodal malignant small round cell tumors and to study the significance of a primary panel (LCA, CK, S-100 and Vimentin) and secondary panel of IHC markers in differential diagnosis of such tumors. Methods: The study was carried out in the Department of Pathology, Pt. B.D. Sharma, UHS, Rohtak. A total of 60 cases of malignant small round cell tumors were selected for IHC and they were classified and categorized accordingly after IHC. Results: Out of the 60 cases of malignant small round cell tumors, there were 19 cases (31.6%) of small cell carcinoma, 16 cases (26.6%) of non Hodgkin lymphoma, 5 cases (8.3%) each of Ewing?s sarcoma and PNET, 4 cases (6.7%) of medulloblastoma, 3 cases (5%) each of rhabdomyosarcoma and seminoma and 1 case (1.7%) each of mesothelioma, neuroblastoma, small cell osteosarcoma, Wilm?stumor and poorly differentiated round cell tumor. Conclusion: Immunohistochemistry has played a valuable adjunctive role for routine hematoxylin and eosin staining in the adequate and accurate categorization of small round cell tumors.