Unusual fixed drug eruption due to rifampicin.

A 24-year-old soldier suffering from borderline tuberculoid leprosy (BT) was admitted to the Leprosy Center, Base Hospital, Lucknow for supervised institutional therapy. He was put on cap RPM 600 mg once a month and dapsone 100 mg daily . The patient developed a solitary itchy erythematous urticarial lesion of 3 .5 cm diameter with typical peau d' orange appear­ ance (Figure 1 ) , on the right side of the chest wall about 1 h after the second monthly dose of RFM. The lesion subsided on its own within 1 h without any residual hyperpigmentation. A similar lesion at the same site was observed following the third monthly dose of RPM which also subsided within 1 h without treatment. At this stage, a clinical diagnosis of FDE was made and all drugs were discontinued. Two days later, the patient was subjected to a provocation test with 600 mg of RFM, following which he developed an urticarial lesion at the same site. The provocation test to dapsone did not evoke any cutaneous reaction. Skin biopsy of the lesion revealed slight dermal oedema and sparse eosinophilic infiltration. Interestingly, this cutaneous response to RFM ceased after the fifth dose of RPM. In our patient, recurrence of a wheal at exactly the same site following administration of RPM is highly suggestive of FDE. Though FDE can be urticarial, the residual hyper­ pigmentation that follows a classical FDE was not seen. Moreover, the histopathology was