Multifocal Colonic Masses as a Presentation of Secondary Extramedullary Plasmacytoma in Relapsing‐Refractory Multiple Myeloma: A Case Report and Review of Literature

Multiple myeloma (MM) is a common plasma cell malignancy; however, extramedullary multiple myeloma (EMM) is an aggressive phenotype in which malignant plasma cells proliferate outside of the bone marrow. Extramedullary plasmacytomas (EMP) are uncommon and gastrointestinal involvement is exceedingly rare. Here, we present a case of multifocal secondary colonic EMP in a patient with relapsed refractory multiple myeloma (RRMM) and review literature demonstrating other cases of secondary colonic EMP.