Squamous cell carcinoma arising in acne conglobata.

A squamous cell carcinoma was found on the back of a man who had had acne conglobata for more than forty years. Squamous cell carcinomas called Marjolin's ulcers may arise in the sites of chronic inflammation and scarring such as thermal burn scars, discoid lupus erythematosus, leg ulcerations, and foci of osteomyelitis. Squamous cell carcinoma has also been reported in all three diseases included in the so-called "follicular occlusion triad": acne conglobata, dissecting cellulitis of the scalp, and hidradenitis suppurativa.