Important Diagnostic Clues for Diagnosing Splenic Marginal Zone Lymphoma in Absence of Splenic Histology.

Splenic Marginal Zone Lymphoma (SMZL) is a rare B-cell neoplasm comprising less than 2% of non-Hodgkin lymphomas. We hereby report a case of SMZL in a 66-year-old female who presented with fever and massive splenomegaly. Peripheral blood smear examination showed atypical lymphoid cells showing variable cytoplasmic processes. Flowcytometric immunophenotyping of peripheral blood showed tumour cells which were found to be positive for CD19, CD79b and showing kappa light chain restriction along with lack of expression for CD5, CD10, CD23, CD103 and lambda. These findings were suggestive of B cell chronic lymphoproliferative disorder. Various differential diagnoses considered in this case were analysed by using different diagnostic clues to arrive at the diagnosis. Bone marrow examination and Immunohistochemical (IHC) analysis showed tumour cells in nodular, interstitial and intrasinusoidal pattern of infiltration which were positive for CD20 and CD79b with kappa light chain restriction and lack of expression of CD5, CD10, CD23 and CD103 which further corroborated the flowcytometric immunophenotyping. The diagnosis of SMZL is arrived at by a combination of diagnostic clues like clinical features, peripheral smear findings, flowcytometric immunophenotyping, morphological and IHC findings in bone marrow biopsy. This case highlights the significance of flowcytometric immunophenotyping and bone marrow biopsy with immunohistochemistry to arrive at a diagnosis of SMZL even in absence of splenic histopathology.