Primary extranodal lymphomas - spectrum of distribution and morphology with immunophenotyping: A 3-year institutional study

Background: Malignant lymphomas arising in extranodal sites are intriguing. The histological types of lymphomas vary from one site to another. This study is undertaken to diagnose and categorize extranodal lymphomas using histochemistry and immunohistochemistry (IHC). Materials and Methods: Formalin processed paraffin blocks and hematoxylin and eosin stained sections were used for routine histology. IHC was done in all cases. Results: We have encountered 31 cases of extra nodal lymphomas over a period of 3 years. The tumors occurred at different sites, including brain, nasopharynx, nose, gastrointestinal tract, thyroid, bone, testis, breast, lung, vagina, and skin. Majority of the cases were B-cell lymphomas, while four cases were T-cell lymphomas. Among the B-cell lymphomas diffuse large B-cell lymphoma was the most common variant. Conclusion: This study reiterates the key role of IHC particularly when the differential diagnosis includes an undifferentiated epithelial malignancy and a high-grade lymphoma in the extranodal sites as the treatment modalities and prognosis are different.