Multiple Myeloma Awareness Month 2026

Did you know? Your plasma cells, which are usually the heroes of your immune system, can sometimes go rogue and turn into villains!

Bone marrow based, multifocal plasma cell neoplasm usually associated with a monoclonal immunoglobulin (M protein) in serum or urine and evidence of organ damage related to the plasma cell neoplasm. Approximately 1.8% of malignant tumor diagnoses are made in the U.S. annually with M:F = 1.2:1. The disease occurs twice as frequently in African Americans compared to Caucasians. It is usually not seen in children, rarely seen in adults under the age of 30; median age of diagnosis being ~70 years. Almost all cases appear to arise in patients with precursor monoclonal gammopathy of undetermined significance (MGUS). When pathologists make a diagnosis of multiple myeloma, they usually need to combine history, clinical manifestations, plasma cell morphology, radiation images and accessory tools such flow cytometry and immunohistochemistry (IHC) as well.

Almost all cases of bone marrow biopsies and cytology aspiration dry slides would need IHC examination for an accurate diagnosis and classification. The IHC would show positivity of plasma cell neoplastic cells, such as positive in CD138, MUM1, EMA, CD79a (almost 100%), CD56 (75 – 80%), CD200 (60 – 75%), CD28 (~40%), CD117 / KIT (20 – 35%), CD20 (10 – 20%), CD52 (8 – 14%), CD10 and occasional myeloid or monocytic markers. The neoplastic lasma cells are also monoclonal light chain dominance, with either kappa or lambda chain. Cyclin D1 positive in presence of t(11;14)(q13;q32), variable expression levels with hyperdiploidy or 11q13 amplification. t(11;14) translocation associated with expression of B cell markers on the clonal plasma cells including CD19, CD20, CD79a . Increased MYC expression may be seen and potentially distinguish multiple myeloma from MGUS. Nearly always CD19 and CD45 negative in contrast to normal plasma cells (except with t(11;14) translocation).