A case of amyloidosis associated with diphenylhydantoin therapy.

Prolonged administration of diphenylhydantoin (DPH) has been implicated as a possible etiologic factor in immunological aberrations and lymphoproliferative disorders. Diphenylhydantoin may account for the increase in susceptibility to lymphoproliferative diseases, as a result of its immunosuppressive effect. We report a case of amyloidosis with monoclonal gammopathy which developed during DPH treatment, without multiple myeloma or lymphoproliferative disorders. The association between DPH and monoclonal gammopathy is very rare, and such a case of amyloidosis associated with DPH has not been reported previously. DPH, however, may have played a role in the development of monoclonal gammopathy, which was the precursor of amyloid protein.