A case of malignant lymphoma with chylothorax and terminal leukemic transformation was reported. A 17-year-old male was admitted to our hospital with a chief complaint of dyspnea on May 16, 1979. X-ray films of the chest revealed a large tumorous shadow in the mediastinum and bilateral pleural fluid. Malignant lymphoma (non-Hodgkin's lymphoma, lymphosarcoma) with chylothorax was diagnosed by examination of the pleural fluid (May-Giemsa Stain, Sudan III-Stain, and biochemical examinations) and lymph node biopsy. Initial combined treatment with chemotherapy and radiation (60Co) appeared to be quite effective, but he died of leukemic transformation without any response to chemotherapy with corticosteroids on November 19, 1979. The etiology and therapy of chylothorax and factors in the development of leukemic transformation of malignant lymphoma were discussed.
