Fixed Drug Eruptions

 

 

FDEs usually appear as solitary, erythematous, bright red or dusky red macules that may evolve into an edematous plaque; bullous-type lesions may be present. FDEs are most commonly found on the genitalia and in the perianal area, although they can occur anywhere on the skin surface . Some patients may complain of burning or stinging, and others may have fever,

malaise, and abdominal symptoms. FDE can develop from 30 minutes to 8 to 16 hours after ingestion of the medication. After the initial acute phase lasting days to weeks, residual grayish or slate-colored hyperpigmentation develops. On rechallenge, not only do the lesions recur in the same location, but also new lesions often appear.

More than 100 drugs have been implicated in causing FDEs, including ibuprofen, sulfonamides, naproxen, and tetracyclines. A haplotype linkage in trimethoprim-sulfa-methoxazole-induced FDE has been documented.

A challenge or provocation test with the suspected drug may be useful in establishing the diagnosis. Patch testing at the site of a previous lesion yields a positive response in up to 43 percent of patients. Results of prick and intradermal skin tests may be positive in 24 percent and 67 percent of patients, respectively.