What exactly is hidradenitis suppurativa?

See below: Hs is a chronic suppurative disease of the apocrine glands in the arm pit, genital and perianal areas. It is due to plugging of the apocrine gland ducts making them dilate and rupture with surrounding tissue inflammation. It is associated with various autoimmune diseases. Irregular sinus tracts form leading to draining tracts and scarring. The lesions frequently become infected with bacteria.

Hidradenitis: Hidradenitis suppurativa (hi-drad-uh-NIE-tis sup-yoo-ruh-TIE-vuh) is rare, long-term skin condition that features small, painful lumps under the skin. They typically develop where the skin rubs together, such as the armpits, the groin, between the buttocks and under the breasts http://www.mayoclinic.org/diseases-conditions/hidradenitis-suppurativa/home/ovc-20200012