This patient has hidradenitis suppurativa (HS) or “acne inversa,” a chronic inflammatory disease that predominantly affects the apocrine gland-bearing areas of the skin. HS is a disease of follicular occlusion. The common sites are the axillae, breasts and inframammary creases, inguinal folds, and gluteal cleft. HS is marked by comedones, inflammatory papules, nodules, cysts, and scarring. The lesions are painful, and the drainage is often foul smelling. The distribution and severity of disease can range from minor to debilitating.

HS is estimated to affect 1% to 4% of the general population and frequently begins in the second to third decade. It is more common in women. Almost 40% of patients with HS report a family history of the disease. About half of patients with HS have breast and armpit involvement and hypertrophic scars.

Smoking is strongly associated with worsening of the disease. Antibacterial soaps and topical antibiotics provide minimal benefit. Oral tetracyclines are used long term for their anti-inflammatory properties, and bacterial cultures may be helpful. Intralesional injections of triamcinolone may hasten resolution of particularly tender areas. Counseling regarding weight loss and smoking cessation should be provided if applicable.

An abscess is a soft-tissue infection with a collection of pus that is walled off from adjacent tissue. Abscesses are warm, tender, fluctuant red-to-purple nodules, which may have an overlying collarette of scale. Bacterial abscesses tend to occur singly and do not typically recur repeatedly in the same general area.

Folliculitis results from infection of the hair follicle. Bacteria, fungi, and even herpes simplex virus can cause folliculitis; however, Staphylococcus aureus is the most common cause. Folliculitis appears as erythematous papules and pustules around a follicle on the face, chest, back, and buttocks. The lesions do not cause large painful nodules about the genitals, axillae, or breasts.

Ruptured epidermal cysts appear as red subcutaneous nodules, much like an abscess. These also tend to be solitary and also do not chronically recur.