Unilateral massive pleural effusion: a presentation of unsuspected multiple myeloma.

Pleural effusion in case of multiple myeloma is usually multifactorial but effusion due to myelomatous deposition of pleura is extremely uncommon. We are reporting a unique case of unsuspected multiple myeloma presenting as left sided massive pleural effusion due to myelomatous deposit in pleura and a rare M-band in the alpha-2 region in serum protein electrophoresis. A 61 year lady presented with cough, weakness and progressive shortness of breath. Examination revealed mild pallor and left sided massive pleural effusion that re-accumulated despite treatment. PAP stained smear of pleural fluid showed a large number of plasma cells and pleural biopsy revealed infiltration of plasma cells. Fiber-optic bronchoscopy was inconclusive. Blood examination revealed high value of alpha-2 globulin. Serum electrophoresis showed M band in alpha-2 region and urine electrophoresis showed faint monoclonal light chain pattern. X-ray skull showed multiple punched out osteolytic lesions. Bone marrow examination revealed hypercellular marrow with atypical plasma cells including binucleate forms in large number (above 55% of nucleated cell population).