Multiple thymoma with myotonic dystrophy.

A case of multiple thymoma associated with myotonic dystrophy is reported. The patient was a 42-year-old man who had two separate encapsulated thymoma in the anterior mediastinum, at 3 cm in diameter on the right side, and at 4 cm in diameter on the left. Extended thymo-thymomectomy was performed. Microscopically, the tumor in the right thymic lobe was predominantly mixed type, and that in the left predominantly epithelial type. Neuromuscular disease appeared to develop, with severe sputum retention in the larynx and he was referred to neurology at 6 months after surgery. On examination, he presented a characteristic hatchet face, muscle atrophy, muscle weakness, percussion myotonia and grip myotonia, and diagnosis was revised to be multiple thymoma associated with myotonic dystrophy. This association is extremely rare. It is difficult to clarify whether this association was a syndrome or coincidence.