Malignant lymphoma after diphenylhydantoin (dilantin) therapy.

A history of prolonged diphenylhydantoin (Dilantin) therapy was reported by 8 of 516 patients (1.6%) with Hodgkin's disease or non-Hodgkin's lymphoma, as compared with 3 of 516 patients (0.6%) with other cancers, and 2 of 516 (0.4%) tumor-free individuals. The findings, together with other published data, suggest a small excess risk of malignant lymphomas in patients receiving long-term treatment with this drug. The immunosuppressive effects of chronic diphenylhydantoin therapy may be involved in the pathogenesis of these neoplasms.