Bronchial plasmacytoma identified by immunoperoxidase technique on paraffin embedded section

A case of bronchial plasmacytoma occurring in a 57-year-old housewife is reported. She had had the productive cough and the "abnormal shadow" in the right lower lobe for three years before admission. On bronchoscopy, a tumor was found in the right main bronchus, large enough to obstruct the air way. The tumor was resected through rigid bronchoscope. Histological impression was "plasmacytoma with local amyloid deposit." M-protein was never detected in the serum or urine. Applying the immunoperoxidase technique for the paraffin section, the plasma cells were found to contain only a single type of immunoglobulin, Ig G-L. The differential diagnosis between plasmacytoma and plasma cell granuloma was made, and plasmacytoma was considered to be one type of extranodal malignant lymphoma.