Monoclonal gammopathy and subsequent multiple myeloma in a patient on chronic diphenylhydantoin therapy.

The development of an IgG lambda-type monoclonal gammopathy and subsequent multiple myeloma in an epilepsy patient on diphenylhydantoin (DILANTIN) therapy for 20 years is reported. We regard the association recorded in this case to be a coincidence despite the known association between the drug and the development of immunosuppression and lymphoma. We recommended periodic examination of the serum proteins in patients receiving diphenylhydantoin in order to detect development of monoclonal gammopathy.