Lesion of a patient with acne conglobata and hidradenitis suppurativa being injected with a steroid. Acne conglobata is a highly inflammatory disease characterised by clogged pores (comedones), nodules, abscesses and draining sinus tracts. 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.