Hidradenitis suppurativa: clinical aspects

Hidradenitis suppurativa (HS), also known as acne inversa is a chronic, recurrent inflammatory disease of the terminal follicle, whose diagnosis following the consensus definition adopted by the second congress of the Hidradenitis Suppurativa Foundation (San Francisco, CA, USA, March 2009) is based on the fulfillment of 3 criteria: • Typical lesions, specifically deep-seated painful nodules: 'blind boils' in early lesions; abscesses, draining sinus, bridged scars and 'tombstone' open comedones in secondary lesions • Typical topography, specifically, axillae, groin, perineal and perianal region, buttocks, infra- and inter-mammary folds; • Chronicity and recurrences. This definition includes only clinical features, as there are not biological or pathological test available to help. Staging of HS and disease severity assessment have been proposed to facilitate patient management and evaluation of clinical course, as well as response to treatment. The use of Hurley staging is very simple in daily practice, describing the degree of inflammation and fibrosis: • Hurley stage I — abscess formation (single or multiple) without sinus tracts and scars; • Hurley stage II — single or multiple, widely separated recurrent abscesses with tract formation and initial scarring; • Hurley stage III — multiple interconnected tracts and abscesses throughout an entire area. This relevant staging system is, however, not sufficient to describe and follow the dynamic changes of the disease, especially during treatment, and the Sartorius score, modified by Revuz, has been widely adopted for clinical trials outcomes evaluation. It is a more composite scoring, assessing points and standard coefficients to the number of sites involved, the counts of typical lesions for each involved region, longest distance between two relevant lesions, presence of normal skin separating lesions. The main differential diagnoses of HS are abscess, carbuncles, furunculosis, infected Bartholin's gland, infected or inflamed epidermal cysts or pilonidal cyst, lymphogranuloma venereum, scrofuloderma, actinomycosis, and cutaneous manifestation of Crohn's disease. Many of these diseases are also associated to HS, confirming the importance of a common pathogenetic inflammatory process. Follicular occlusion associate HS to acne, pilonidal cysts, dissecting cellulitis of the scalp, constituting the acne triad or tetrad. It has been estimated that a 30% of HS patients suffers of Crohn’s disease, while 5% presents pyoderma gangrenosum. Another strong association or complication depending on the controversial interpretation of the disease course is peripheral or axial arthopathy, and enthesytis eventually as part of the SAPHO syndrome. The main complications of long standing untreated HS include: anemia and chronic malaise, major depression, amiloidosis, acute infections, such as cellulitis, fistula formation into urethra, bladder or peritoneum, lymphatic obstruction and lymphedema, squamous cell carcinoma development.