Synchronous dual haematological malignancies – Multiple myeloma and low-grade B-cell lymphoma – A case report and review of the literature

Synchronous diagnosis of two different haematological malignancies of a non-Hodgkin lymphoma and multiple myeloma (MM) is very rare. We report the case of the coexistence of low-grade B-cell lymphoma and MM. The patient was a 79-year-old male who presented with severe transfusion-dependent anaemia and had all CRAB features. Bone marrow flow cytometry revealed lymphocytes and plasma cells which both expressed different light chain restrictions with B-cell showing kappa light chain and plasma cells showing lambda light chain. Serum protein electrophoresis revealed an immunoglobulin G lambda band of 1.42 g/dl. The patient was evaluated extensively to rule out lymphoplasmacytic lymphoma and other plasmacytic lymphomas with positron emission tomography-computed tomography and molecular workup. He was started on therapy with bortezomib–dexamethasone–rituximab. The patient unfortunately expired due to sepsis. The treatment of such an unusual presentation remains difficult. Few case reports of MM with synchronous non-Hodgkins lymphoma are present. We present this case due to the rarity of such a presentation.