[A case of malignant lymphoma arising from chronic pyothorax; usefulness of magnetic resonance imaging (MRI) for diagnosis].

A 79-year-old man had a history of pneumothorax induced to treat pulmonary tuberculosis when he was 40 years old, and of chronic pyothorax when he was 60 years old. He was admitted to our hospital because of chest pain and swelling of the right lateral chest wall. Soft tissues of the chest wall and rib had been destroyed, and a fistula had formed at the skin. The diagnosis was confirmed by examination of a biopsy specimen from the chest wall tumor. The tumor was successfully treated by radiation therapy. 67Ga scintigraphy, CT, and MRI were useful for diagnosis and follow up. Pyothorax and the tumor could be distinguished only with MRI.