[Anticonvulsant hypersensitivity syndrome to carbamazepine]

In a 39-year-old woman an anticonvulsant therapy was initiated because of focal attacks in the left arm and face. The patient experienced generalized maculopapular skin rashes in response to each of four chemically similar anticonvulsant drugs: phenytoin, carbamazepine, primidone and clonazepam. During administration of carbamazepine the clinical features included fever, hepatitis and hematological eosinophilia in addition to the skin rash (anticonvulsant hypersensitivity syndrome). The anticonvulsant hypersensitivity syndrome is defined as an idiosyncratic reaction caused by disturbed drug metabolism. Positive lymphocyte-transformation tests with carbamazepine and phenytoin indicate an immunological mechanism underlying the rashes in our patient. Patch testing with the four anticonvulsant drugs gave positive results only with carbamazepine. Skin biopsy showed the histological features of a delayed-type allergy. The anticonvulsant therapy was continued with a chemically unrelated preparation, valproic acid; this drug is well tolerated and has proved appropriate for prevention of seizures.