Quinidine-induced lichenoid and eczematous photodermatitis.

We report 6 cases of photodistributed rashes due to oral administration of quinidine: 4 cases with a lichen-planus-like eruption and 2 with an eczematous dermatitis. The casual relationship between the drug and the eruption was established mainly by means of circumstantial evidence. It was further strengthened by an in vitro challenge test in 4 cases and by a rechallenge in 2 patients. The in vitro challenge test used was the macrophage migration inhibition test, which can be of diagnostic aid whenever a rechallenge of the patient is contraindicated. Quinidine-induced lichenoid eruption in a photodistribution seems to be more common than previously reported. Physicians should be aware of this type of drug eruption.