A case of allopurinol-induced fixed drug eruption confirmed with a lymphocyte transformation test

Allopurinol is one of the causative drugs that induce fixed drug eruption (FDE). The lymphocyte transformation test (LTT) is a safe and reliable diagnostic procedure for drug allergy, but is reported to be rarely positive in patients with FDE. In the current case, we performed an LTT and successfully confirmed allopurinol as the offending drug. This case report suggests that an LTT should be an optional diagnostic tool for FDE or delayed reaction due to allopurinol.