Signet ring lymphoma: The import of immunohistochemistry in resolving diagnostic dilemmas.

Signet ring cell lymphomas are a rare subtype of non Hodgkin lymphoma characterised by malignant lymphoid cells with cytoplasmic inclusions that displace the nucleus and imparts a "signet ring" appearance. This poses a diagnostic challenge as it can be mistaken for an adenocarcinoma or any other epithelial malignancy. A 54yr old male presented with a 6month history of generalised lymphadenopathy. Examination of excision biopsy of the lymph nodes show effacement of architecture by sheets neoplastic cells with abundant cytoplasm distended by eosinophilic amorphous substances. Immunohistochemistry with a panel of three monoclonal antibodies [LCA, CD20, and CD3] confirmed these cells to be of lymphoid origin.