Generalized pustular psoriasis or drug-induced toxic pustuloderma? The use of patch testing.

Pustular psoriasis is a rare but serious form of psoriasis. Clinically it may be difficult to differentiate from a pustular drug reaction. We report a case of a generalized pustular eruption triggered by exposure to amoxycillin in a patient with chronic psoriasis. Patch testing to 1% and 5% amoxycillin preparation confirmed a delayed hypersensitivity reaction.