Probable Anticonvulsant Hypersensitivity Syndrome Due to Fosphenytoin in a Pediatric Patient with Streptococcus pneumoniae Meningitis.

An 8-year-old previously healthy girl with Streptococcus pneumoniae meningitis developed probable anticonvulsant hypersensitivity syndrome (AHS) within 5 days of starting fosphenytoin. She experienced fever, rash, periorbital edema, profound hepatotoxicity and coagulopathy. Her sudden and dramatic rise in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) to greater than 80 times the upper limit of normal in combination with an elevated INR were very concerning. Mortality from AHS has been correlated with the degree of hepatic involvement. Fosphenytoin was immediately discontinued and, within 48 hours, AST, ALT and INR began to decrease and were within normal limits by hospital day 23. Prompt recognition of probable AHS and immediate discontinuation of fosphenytoin resulted in an abrupt reversal of clinical signs and laboratory values associated with potential hepatic failure in a pediatric patient.