[Pulmonary adenocarcinoma in myasthenia gravis--autoimmunity and late development of malignancy].

We report a 75-year-old man with myasthenia gravis for many years, who was hospitalized because of cough, fever, and dyspnea. Chest x-ray revealed a bilateral pleural effusion. Adenocarcinomatous cells were found in the pleural fluid. Computerized tomography of the chest showed widespread pulmonary dissemination of the tumor. The relationship between myasthenia gravis, an autoimmune disease involving the motor end-plate, and malignancy (thymoma) has been widely recognized. Current literature documents few reports of lung malignancies with concurrent development of myasthenia gravis. A tentative explanation, based on current research, is provided for the possible role of myasthenia gravis and the late development of lung cancer. Moreover, a model for the autoimmune phenomenon and the development of late malignancies is provided with explicit explanations. It is important to search for occult, developing malignancies in newly diagnosed autoimmune diseases.