A Case Presenting with Splenic Infarct Diagnosed as Primary Bone Marrow CD5 Positive DLBCL: A Clinicopathological Correlation.

De novo CD5+ Diffuse large B cell lymphoma (DLBCL) is a rare and aggressive subtype of DLBCL. It is a distinct clinicopathologic entity with complex molecular profile and poor prognosis. A 59 year old female presented with pyrexia of unknown origin since 1 month. On examination, there was severe pallor, hepatosplenomegaly and no palpable lymphadenopathy. Complete blood count revealed bicytopenia with normal total leucocyte count. Liver and renal function tests were normal. Ultrasonography abdomen revealed splenic enlargement with two focal lesions attributed to either splenic abscess or infarcts. Patient was being managed as splenic infarct but continued to have bicytopenia. Further investigation showed elevated serum ferritin, triglycerides and LDH. With a clinical suspicion of infection and haemophagocytic lymphohistiocytosis bone marrow aspiration (BMA) and biopsy (BMBx) was done. BMA showed extensive haemophagocytosis and ~7.4 % large lymphoma-like cells. On this basis PET-CT was suggested which showed enlarged spleen with diffuse uptake. BMBx showed nodular and intrasinusoidal collection of abnormal lymphoid cells. On immunohistochemistry, these cells were positive for CD20, CD5, MUM1, BCL-2, BCL-6 and negative for CD3, CD10 and CD23. CD34 highlighted focal intrasinusoidal pattern. The complete clinicopathological profile suggested the diagnosis of de novo CD5+ DLBCL, with primary hepatosplenic pattern of involvement. CD5+ DLBCL presenting as splenic infarct is very rare. This case was unusual as the diagnosis of a primary aggressive lymphoma with haemophagocytosis was established in a patient who presented with fever and splenic infarct without lymphadenopathy. This indicates the importance of good morphological assessment of a bone marrow aspirate and biopsy to make a correct diagnosis.