Fatty replacement of lymph nodes mimicking lymphoma relapse

A 70-year-old man was treated successfully for diffuse histiocytic lymphoma involving the left ilium and bone marrow. He received radiation therapy to the left hip for stabilization, then eight cycles of intense (COP-BLAM) chemotherapy. Restaging at the completion of therapy demonstrated a normal physical examination, laboratory values, bone scan, bone survey, and abdominal computerized tomographic scan. One month after restaging he developed rapidly enlarging lymphadenopathy. Biopsy of an axillary node showed complete fatty replacement without lymphoma, and the patient remains in remission 16 months later. Recent reports of residual masses after lymphoma therapy have demonstrated fibrous replacement, necrotic tissue, thymic hyperplasia, and vascular anomalies mimicking lymphadenopathy. Lymph node enlargement may be due to nonmalignant causes, including fatty replacement, and not due to recurrent lymphoma.