Hidradenitis Suppurativa

Definition/diagnostic criteria Hidradenitis suppurativa (HS) is a chronic, inflammatory skin condition characterised by recurrent, painful nodules, abscesses, and scarring, predominantly in apocrine gland-bearing areas. It is believed to result from follicular occlusion, leading to secondary inflammation and infection. Diagnosis is primarily clinical, based on the recurrent nature of lesions and their typical distribution.

Epidemiology HS is underdiagnosed and its prevalence is underestimated. It is estimated to affect about 1% of the population. The condition typically presents after puberty, with a peak incidence in the second and third decades of life. It has a female predominance and is associated with comorbidities such as obesity, metabolic syndrome and inflammatory bowel disease.

Diagnosis
Clinical features: HS is characterised by recurrent, painful nodules, abscesses, and sinus tracts, often with malodorous discharge. Lesions predominantly occur in intertriginous areas, such as the axillae, inguinal, and anogenital regions. Chronic cases lead to scar formation and can cause significant psychosocial impact.

Investigations: Diagnosis of HS is primarily clinical. Investigations are not typically required for diagnosis but may be conducted to rule out other conditions or to assess for complications. These may include microbiological swabs of pus or discharging sinuses, primarily to exclude secondary infection rather than to confirm a diagnosis of HS.

Ultrasound, MRI, or CT scans may be used in complex or severe cases to map the extent of sinus tracts and involvement of underlying structures.

Treatment Treatment aims to reduce flare-ups, manage pain and inflammation, and prevent the formation of new lesions and scars. Management should be tailored to disease severity, patient comorbidities, and response to previous treatments.

• Topical treatments: Clindamycin is recommended as a first-line topical treatment.
• Antibiotics: Oral tetracycline or a combination of clindamycin and rifampicin (usually under secondary care) may be used for their anti-inflammatory properties.
• Hormonal therapies: Such as oral contraceptives or antiandrogens, may be considered, particularly in females with PCOS or a premenstrual flare of symptoms.
• Biologics: Adalimumab is the only biologic licensed for use in HS and is recommended for patients with moderate to severe HS who have not responded to conventional systemic therapies – clearly, these patients will be under secondary care.
• Surgical interventions: Including deroofing, local excision, or more extensive surgical procedures, may be necessary in severe or refractory cases.

Management should also include lifestyle advice on weight management, smoking cessation, and the avoidance of skin trauma.

Prognosis HS is a chronic, relapsing condition. Early diagnosis and management are crucial in preventing disease progression, minimising complications, and improving quality of life. Patients often experience a significant psychosocial impact, and a multidisciplinary approach, including psychological support, is recommended. Long-term management may involve dermatologists, surgeons, and other specialists, depending on the severity and complications of the disease.