Ethambutol-induced bullous skin lesions in mycobacterium kansasii lung infection

Mycobacterium kansasii is the second most common cause of nontuberculous mycobacterial (NTM) lung disease after Mycobacterium avium complex infection in the United States.^[1] The first-line therapy for M. kansasii is a three-drug regimen including rifampin, isoniazid, and ethambutol. We present a case of a patient with pulmonary M. kansasii who developed bullous skin lesions while receiving this regimen and again after rechallenge with ethambutol. In patients with intolerance to one of the first-line antibiotics, a multidisciplinary team approach to starting second-line agents is needed. Ethambutol should be included in the differential diagnosis of drug-induced bullous skin lesions in treated patients with NTM, who develop new onset rash with blisters or ulceration.