[Multiple myeloma associated with phenytoin (diphenylhydantoin) therapy]

The occurrence of multiple myeloma is described in a patient receiving phenytoin (diphenylhydantoin) for 43 years. In this article, five cases of multiple myeloma and one of immunoblastic lymphadenopathy associated with diclonal gammopathy diagnosed after longterm phenytoin therapy are reviewed. These cases are characterized by lymphadenopathy, hepatosplenomegaly, and no or equivocal bone lesions, which are quite unusual in multiple myeloma. Because of the association of lymphomas with phenytoin, the role of the drug in the etiology of multiple myeloma or plasma cell dyscrasias is still in controversy, but highly suspected. It is suggested that a periodic examination of patients receiving phenytoin may be useful in an early detection of M-component. The possibility of reversing multiple myeloma by removal of phenytoin early in the course of the disease should be investigated.