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February 2002
Case submitted by Adrienne M. Moore, C.
Whitney Hannon, MD, and Suephy C. Chen, MD
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CASE:
A 43-year-old woman has a widespread rash that developed
three weeks after beginning phenytoin therapy as prophylaxis
for seizure. She discontinued the therapy after 29 days and
presented to the ED 5 days later with fever, myopathy, and
anorexia. On physical examination, she is febrile, and widespread
erythematous patches and lymphadenopathy are evident. Laboratory
studies reveal hepatitis and a phenytoin level within the
therapeutic range.
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This patient has all of the primary symptoms of phenytoin
hypersensitivity syndrome, including dermatitis, hepatitis,
lymphadenopathy, and fever. Secondary diagnostic criteria
include anemia, nephritis, anorexia, thrombocytopenia, eosinophilia,
myopathy, and pulmonary infiltration. Initially, when the
patient was given intravenous methylprednisolone and topical
triamcinolone, her hepatitis worsened and pancreatitis, anorexia,
and thrombocytopenia appeared. Eventually, however, her condition
improved and the rash resolved, marked by desquamation and
postinflammatory hyperpigmentation. At discharge, on day 9,
the patient's liver function was returning to normal and all
other laboratory values were within normal limits.
Phenytoin hypersensitivity syndrome is caused by a mutation
in the epoxide hydrolase enzyme. Safe alternatives include
valproic acid and benzodiazepines, which are structurally
different and metabolized by different pathways.
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Ms. Moore is a medical student at the University of Michigan
Medical School in Ann Arbor, Michigan, Dr. Hannon is a resident
in the department of dermatology at Emory University School of
Medicine in Decatur, Georgia, and Dr. Chen is assistant professor
of dermatology at Emory University School of Medicine in Atlanta.
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