Mycobacterium kansasii infection in a patient presenting with porphyria cutanea tarda

Mycobacterium kansasii, an atypical mycobacterium, is an uncommon cause of cutaneous and joint disease in immunocompetent patients. We report an unusual case of infection with this organism in a patient who initially presented with porphyria cutanea tarda (PCT), and who was noted also to have a crusted ulcer over the middle phalanx and swelling of the proximal interphalangeal joint of the right middle finger. The cutaneous ulcer healed with minocycline, but the joint disease required a combination of rifampicin and ethambutol before a therapeutic response was obtained.