A 64-year-old man underwent a left pneumonectomy for a benign bronchial stenosis in 1968. In 1997, a left parietal thoracic tumour: T-type malignant non-Hodgkin's lymphoma (MNHL) was detected. It was treated by chemotherapy and radiation therapy. After 6 years follow-up, the patient is alive and in remission. We have found only one case of such a lymphoma in the literature. It could be classified as pyothorax-associated lymphoma from which there are several published cases especially in Japanese literature.