Hiradentitis Suppurativa
Definition: Hidradenitis SUppurativa (HS), also known as acne inversa, is a chronic inflammatory skin condition that affects the apocrine-gland-bearing skin. It is characterized by painful, persistent deep-seated nodules, abscessed as skin tunnels that may develop purulent discharge and result in scarring.
Etiology: HS development may have genetic, environmental and behavioural influences. There is an autosomal dominant transmission pattern of HS. A loss-of-function mutation of the y- y-secretase complex involved in the Notch signalling pathway has been identified as a cause of HS. Other mutations include the DCD, PSTP 1P1, SOX9 and KLF5 genes. Environmental and behavioural factors are also relevant as individuals with HS often have co-morbidities that may lead to increased skin friction, sweat overproduction and retention and hormonal changes, which can increase the progression and severity of HS.
Epidemiology: The global prevalence of HS is variable, and may affect up to 4.1% of the population. In North American and European patients, HS is three times more women in females than males. In South Korea and Japan, HS is more common in males. HS typically manifests at puberty and is most active between 20 – 40 years of age. It may resolve at menopause in women. Risk factors include a family history of HS, obesity and metabolic syndromes, cigarette smoking, African ethnicity, IBD- particularly Crohn’s disease and other skin disorders.
Signs: Characteristic primary HS nodules are deep nodules typically 0.5- 2cm in size and can persist for days to months. The lesions may resemble recurrent, rupture-prone boils and have a serosanguinous discharge which may become purulent. The affected areas include the axilla, neck, inframammary folds, inner upper thighs, and anogenital region. The characteristic features of HS also include double open-ended comedones, painful firm papules and nodules, pustules, abscesses, draining sinuses linked to inflamed lesions, and atrophic and hypertrophic scars. The scars or plaques may cause architectural distortion and “tombstone” comedones.
Symptoms: Many patients report prodromal symptoms like burning, stinging, pain pruritus or hyperhidrosis which may precede a lesion by 12 hours. Triggers include menstruation, obesity, stress, heat, hormonal changes, and perspiration.
Differentials: Staphylococcal skin infection, cysts, Cutaneous Crohn’s disease, Anogenital Crohn’s disease.
Diagnosis: HS may be diagnosed clinically. Three components of a triad must be met to diagnose HS: characteristic lesions, typical distribution and presence and recurrence of lesions. Skin biopsy can help confirm an HS diagnosis. Histopathological features include follicular occlusion and hyperkeratosis, infundibular follicular epithelial hyperplasia, keratin plugging, epidermal psoriasiform hyperplasia and plasmacytic infiltrate.
Treatment: General measures for treatment include smoking cessation, weight reduction, analgesics, loose-fitting clothing and improved hygiene. Specific medical treatment includes topical antibiotics or benzoyl peroxide, systemic antibiotics and oral hormonal therapies and immunomodulatory treatments. Procedural measures include incision and drainage of acute abesses and local excision of persistent nodules. Laser ablation of nodules, hair removal and radical excision of an affected area.
References:
- Ballard K, Shuman VL. Hidradenitis Suppurativa. In: StatPearls. Treasure Island (FL): StatPearls Publishing; May 6, 2024.
- Hidradenitis Suppurativa (Acne Inversa): A Complete Picture – DermNet. dermnetnz.org. https://dermnetnz.org/topics/hidradenitis-suppurativa
- Bukvić Mokos Z, Markota Čagalj A, Marinović B. Epidemiology of hidradenitis suppurativa. Clin Dermatol. 2023;41(5):564-575. doi:10.1016/j.clindermatol.2023.08.020