Mononucleosis and hepatic failure associated with diphenylhydantoin treatment in an infant.

Diphenylhydantoin-induced hepatitis and mononucleosis are uncommon in children. The occurrence of these two diseases in the same individual, with progression to hepatic failure is rare and has not been reported in infants. This report represents a 6-month-old male infant who developed an infectious mononucleosis-like syndrome and hepatic failure 16 days after diphenylhydantoin administration. He took this anticonvulsant for controlling seizures after a head injury. Fever, skin rash, hepatosplenomegaly, lymphadenopathy, and atypical lymphocytosis led to the initial diagnosis of infectious mononucleosis. However, negative heterophil antibody did not support the diagnosis. Jaundice ensued in the following course and became more and more profound. Meanwhile, physical examination showed shrinking in liver size. Negative virology studies, including Epstein-Barr virus, cytomegalovirus, and hepatitis B virus, excluded them as causative agents. The patient lapsed into a stage I hepatic coma, but gradually recovered clinically and biochemically after eight successive exchange transfusions and supportive care. Two liver biopsies were performed 20 and 50 days after the onset of disease, respectively. Remarkable hepatic parenchymal loss, cholestasis, and fatty change were found on histologic examination of the first biopsy specimen, and portal fibrosis was noted on the second.