Persistent Abdominal Pain with an Uncommon Presentation of Multiple Myeloma: A Case Study

Multiple myeloma (MM) is a widespread malignant condition characterized by the proliferation of transformed plasma cells in the bone marrow, disrupting its normal functions and infiltrating adjacent bone tissues. While typically confined to the bone marrow, in rare instances, patients may develop extramedullary disease. In these uncommon scenarios, the involvement of lymph nodes poses a diagnostic challenge for practitioners in their daily routines. This report details the case of a 49-year-old male experiencing chronic abdominal pain. A computed tomography (CT) scan revealed enlargement of retroperitoneal and mesenteric lymph nodes. Biopsies confirmed a plasma cell infiltrate positive for CD138 and kappa light chain, leading to the diagnosis of multiple myeloma with extramedullary localization in lymph nodes. Our case underscores the rare presentation of extramedullary involvement in multiple myeloma, characterized by an atypical clinical manifestation.