Small-lymphoid cells and myeloid antigen expression in a patient with IgG myeloma: A case report.

Multiple myeloma is defined as a malignant proliferation of a single clone of plasma cells resulting in monoclonal immunoglobulin production. Due to the number of plasma cell morphological variants, difficulty is often faced during morphological diagnosis. The current study describes the case of a 49-year-old woman presenting with atypical plasma cell morphology detected by a bone marrow examination. Flow cytometric immunophenotyping determined the nature of the neoplastic cells as monoclonal myeloma cells with myeloid antigen expression. Serum electrophoresis with immunofixation and subsequent clinical findings confirmed this diagnosis. Therefore, the immunophenotyping of plasma cells in myelomas may be useful for the diagnosis of cases with atypical plasma cell morphology.