Diffuse primary plasmacytoma of the lung.

Primary plasmacytoma of the lung is a rare tumor, thus presenting a diagnostic challenge to the clinician. So far, approximately 20 cases have been verified by immunohistochemistry. We describe an elderly patient presenting with progressive dyspnea on exertion, dry cough, weight loss and malaise. The main finding on plain chest radiography was a diffuse infiltration of pulmonary parenchyma in the lower parts of both lungs and in the middle part of the right lung. The histology of the open lung biopsy of the right middle lobe revealed massive and diffuse infiltration by well differentiated plasma cells with extracellular deposits of amyloid. The plasma cells and amyloid expressed a monoclonal lambda light chain. No monoclonal spike was shown by serum and urine immunoelectrophoresis. A skeletal survey and bone marrow biopsy specimen excluded a disseminated disease and a diagnosis of extramedullary plasmacytoma was made. The patient was considered for VI courses of VMCP chemotherapy after which a complete regression on chest roentgenography was evident. Almost five years after the diagnosis the patient is still alive without any evidence of disease recurrence or dissemination.