Extramedullary Involvement of Lymph Nodes in Multiple Myeloma

Myeloma multiplex is a malignant disease of bone marrow plasma cells. It is usually confined to the bone marrow, but in rare cases, patients can develop extramedullary disease. The involvement of lymph nodes is rare and can be a diagnostic challenge. Here, we describe a 36-year-old male patient who presented with abdominal pain and discomfort initially. An abdominal ultrasound followed by computed tomography (CT) revealed retroperitoneal and mesenteric lymph node enlargement. Biopsies of the abdominal lymph node and infiltrated colon showed a plasma cell infiltrate positive for CD79α, CD38, CD138, kappa light chain and VEGF2. Multiple myeloma with extramedullary localization was diagnosed. After six cycles of chemotherapy consisting of doxorubicin, dexamethasone and thalidomide followed by autologous haematopoietic cell transplantation, the patient achieved complete remission. Specifically, a CT scan after therapy showed enlarged lymph nodes in the abdomen, but PET CT scans did not detect any metabolically active foci. Thee years after the completion of therapy, the patient remains in remission. This case illustrates a rare presentation of extramedullary myeloma involving the abdominal lymph nodes, which could have been potentially mistaken for a lymphoid malignancy.