Multiple myeloma with monoclonal immunoglobin M as a differential diagnosis of Waldenstrom macroglobulinemia: a case report

Immunoglobulin M (IgM) multiple myeloma (MM) has rarely been described in sub-Saharan Africa and is difficult to distinguish from other IgM-related malignant hemopathies such as Waldenström macroglobulinemia (WM). We present here the case of a 67-year-old patient with IgM monoclonal gammopathy in the Clinical Hematology Unit of the National Center of Blood Transfusion in Dakar, Senegal. Medical investigations allowed excluding pathologies such as chronic lymphocytic leukemia, WM and monoclonal gammopathy of undetermined significance. Clinical manifestations, elevated serum IgM levels and bone marrow plasmacytosis associated with osteolytic bone disease suggested a diagnosis of IgM multiple myeloma. This diagnostic was established according to the 2014 International Myeloma Working Group criteria. Diagnostic confusion between IgM MM and other causes of IgM monoclonal gammopathy had to be avoided. Indeed, IgM MM had a different prognosis and management compared to other causes. A multidisciplinary approach and follow-up were important to improve the prognosis. Keywords: IgM multiple myeloma; Waldenström macroglobulinemia; differential diagnosis Received: March 12th, 2024 Accepted: October 10th, 2024 https://dx.doi.org/10.4314/aamed.v18i1.11