4.1.4 Hidradenitis Suppurativa

Acne inversa; inverse acne; suppurative hidradenitis; pyodermia fistulans sinifica; hidrosadenitis suppurativa; Verneuil disease.

Prevalence 0.04% (range 0.03-1%), annual age- and sex-adjusted incidence 6.0 per 100,000. Increasing incidence over the past four decades particularly among women. Male: female ratio 1:1.2 to 1:3.3.

The exact pathogenetic mechanism of hidradenitis suppurativa remains unclear. Potential causes are related to genetic, environmental, endocrine and microbiological factors. Follicular keratinocyte differentiation, adipocyte function and inflammation seem to be the major molecular pathogenetic pathways. Sporadic disease 70%, familial disease 30% (mutations at the nicastrin domain within the γ-secretase complex, chromosome 19p13). Smoking (12.6x), obesity (1.1x with every BMI unit; 18% from BMI>30) and metabolic syndrome (4.5x) are major predisposing factors.

Mostly intertriginous occurrence in decreasing order of frequency: inguinal, axillary, perineal and perianal, submammary and/or intermammary fold in women, buttocks, mons pubis, scalp, retroauricular area and eyelids.

Combination of anatomical classification (Hurley I, II, III) and severity classification (mild, moderate, severe; IHS4 score). IHS4 can also evaluate HS severity in a dynamic manner.

IHS4 (Points) =

number of nodules x 3 +
number of abscesses x 2 +
number of draining tunnels x4

Mild HS ≤ 3 points

Moderate HS 4 - 10 points

Severe HS ≥ 11 points

Syndromic hidradenitis suppurativa diseases (follicular occlusion, Bazex-Dupré-Christol, Down’s, KID, PAPASH, PASS, PASH, and SAPHO syndromes, Dowling-Degos disease).

Heterogeneous histological pattern with hyperplasia of hair follicular epithelium, hyperkeratosis of the terminal follicles, pronounced perifolliculitis, follicle rupture, epidermal psoriasiform hyperplasia, subepidermal and deep cellular inflammatory infiltrate, pronounced acute/chronic dermal inflammation, involvement of apocrine glands and involvement of the subcutis (fat tissue).

Acute: Recurrent, painful, deep-seated, inflamed nodules with burning, itching, local warmth, and hyperhidrosis.

Chronic: Multiple abscesses, double pseudocomedones, tunels, foul-smelling discharge, scarring, ulceration.

Staphylococcal infection (furuncle, carbuncle), cutaneous Crohn’s disease, primary or metastatic tumors, lymphogranuloma venereum, apocrine abscess, rare diseases (cutaneous actinomycosis, tuberculosis cutis colliquativa).

Prevention: Weight loss and tobacco abstinence, pain management, treatment of superinfections.