This 63-year-old female presented with the complaint of left chest pain of approximately 4 months duration. Physical examination revealed that the pain was along the distribution of the left sixth intercostal nerve. Chest film showed a posterior mediastinal mass with partial collapse of T6. A lytic lesion of the right distal clavicle was noted on subsequent radiological examination. A bone scan revealed increased uptake in thoracic vertebrae. Serum alkaline phosphatase was elevated slightly (143 U/L). Serum protein electrophoresis was normal, while urine protein electrophoresis showed a monoclonal spike in the Gamma region. A bone marrow study was non-diagnostic.

A thoracotomy was performed after an unsuccessful needle biopsy. At thoracotomy, a 3-cm posterior mediastinal mass was identified that extended to within 1-2 mm of the aorta and into the interspace between the ribs.