Fixed drug eruptions: presentation, diagnosis, and management.

Fixed drug eruption (FDE) is a well-defined, circular, hyperpigmenting plaque that recurs as one or a few lesions always in fixed locations upon ingestion of a drug. FDE commonly occurs on the genitals, lips, trunk, and hands. Although the lesions are distinctive, the diagnosis of FDE often is missed because it shares none of the characteristics of more common morbilliform drug rashes. The diagnosis can be confirmed by histopathologic examination of a small punch biopsy specimen. Drug avoidance is the mainstay of treatment, and antihistamines can reduce associated pruritus. Raising awareness of this condition will increase the likelihood of prompt diagnosis leading to resolution within days to weeks after the offending drug is discontinued.