Hidradenitis suppurativa lesion in a 33 year old Hispanic female patients armpit that has been treated with deroofing. Hidradenitis suppurativa, also known as acne inversa, is caused by the blockage of the apocrine glands typically found in the armpits, buttocks, groin and back. Apocrine glands are specialised sweat glands that open into a hair follicle before reaching the skin. The glands become blocked due to overactivity, giving rise to inflammation, infection and abscess formation. Deroofing involves removing the top layer of the lesion, draining any pus and cleaning away damaged tissue.