Synonyms: Apocrinitis, hidradenitis axillaris, abscess of the apocrine sweat glands, acne inversa.
AGE OF ONSET From puberty to climacteric.
SEX Affects more females than males; estimated to affect 4% of the female population. Males more often have anogenital whereas females experience axillary involvement.
RACE All races.
HEREDITY Mother-daughter transmission has been observed. Families give a history of nodulocystic acne and hidradenitis suppurativa occurring separately or together in blood relatives.
Etiology Unknown. Predisposing factors: obesity, smoking, and genetic predisposition to acne.
PATHOGENESIS Keratinous plugging of the hair follicle → dilatation hair follicle and secondarily of the apocrine duct → inflammation → bacterial growth in dilated follicle and duct → rupture → extension of suppuration/tissue destruction → ulceration and fibrosis, sinus tract formation → scarring.
Symptoms Intermittent pain and marked point tenderness related to abscess.
SKIN LESIONS Open comedones, double comedones → very tender, red inflammatory nodules/abscesses (Fig. 1-17) → resolve or drain purulent/seropurulent material → moderately to exquisitely tender sinus tracts → fibrosis, "bridge" scars, hypertrophic and keloidal scars, contractures (Figs. 1-17 and 1-18). Rarely, lymphedema of the associated limb.
Distribution Axillae, breasts, anogenital area, or groin. Often bilateral, but may extend over entire back, buttocks, perineum involving scrotum or vulva (Figs. 1-19 and 1-20), and scalp.
Associated Findings Cystic acne, pilonidal sinus. Often obesity.
BACTERIOLOGY Various pathogens may secondarily colonize or "infect" lesions. These include S. aureus, streptococci, Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa.
DERMATOPATHOLOGY Keratin occlusion of hair follicle, ductal/tubular dilatation, inflammatory changes limited to follicular apparatus → destruction of apocrine/eccrine/pilosebaceous apparatus, fibrosis, or pseudoepitheliomatous hyperplasia in sinuses.
Differential Diagnosis
Painful papule, nodule, abscess in groin and axilla: furuncle, carbuncle, lymphadenitis, ruptured inclusion cyst, painful lymphadenopathy in lymphogranuloma venereum, or cat-scratch disease. Also: donovanosis, scrofuloderma, actinomycosis, sinus tracts, and fistulas associated with ulcerative colitis and regional enteritis.
The severity varies considerably. Patients with mild involvement with recurrent, self-healing, tender red nodules often do not seek therapy. Usually a spontaneous remission with age (>35 years). Some course is relentlessly progressive, with marked morbidity related to chronic pain, draining sinuses, and scarring, with restricted mobility (Figs. 1-19 and 1-20). Rare complications: fistulas to urethra, bladder, and/or rectum; anemia; amyloidosis.
Hidradenitis suppurativa is not simply an infection, and systemic antibiotics are only part of the treatment program. Combinations of (1) intralesional glucocorticoids, (2) surgery, (3) oral antibiotics, and (4) isotretinoin are used.
ACUTE PAINFUL NODULE AND ABSCESS Intralesional triamcinolone (5 to 20 mg/mL) into the wall followed by incision and drainage of abscess.
CHRONIC LOW-GRADE DISEASE Oral antibiotics: doxycycline or minocycline 100 mg BID; or a combination of clindamycin, 300 mg BID with rifampin 300 mg BID for 10 weeks; resolution may take weeks or months.
PREDNISONE Concurrently, if pain and inflammation are severe: 14- to 21-day prednisone taper, starting at 1 mg/kg.
ORAL ISOTRETINOIN Not useful in severe disease, but useful in early disease to prevent follicular plugging and when combined with surgical excision of individual lesions. TNF-α inhibitors (e.g., infliximab) show promising results in severe cases.