The patient described, a 51-yearold woman, had diplopia and cephalgia of two weeks' duration. On admission, the radiologic evaluation revealed a mass in the sphenoid sinus, multiple lesions in the calvarium and a solitary lung mass. Biopsy of the lung mass revealed an atypical plasmacytic infiltration. Laboratory findings confirmed the diagnosis of light-chain myeloma presenting with a pulmonary plasmacytoma and cranial nerve involvement.