[Pseudomononucleosis induced by diphenylhydantoin (author's transl)].

The authors report a patient who developed a mononucleotic syndrome after 2 months treatment with diphenylhydantoin. The clinical and biological criteria needed to establish the diagnosis of pseudomononucleosis are listed, while other possible causes described in the literature have been excluded. Complications which may occur during anti-convulsant therapy with diphenylhydantoin are reviewed and the few cases of pseudomononucleosis in the literature noted. Diagnosis was established through eliminating other possible causes, as the only definite test-drug induced reaction-is hazardous to the patient.