Hidradenitis suppurativa is an inflammatory skin disease that is characterised by recurrent boil-like lumps (abscesses) that culminate in pus-like discharge, difficult-to-heal open wounds and scarring. It commonly occurs on apocrine sweat gland-bearing skin such as in the groin, the underarms and under the breasts. It is also known as 'acne inversa'.
What causes hidradenitis suppurativa and who gets it?
The exact cause of hidradenitis suppurativa remains unclear. What is understood is that the condition is a disorder of follicular occlusion. This begins with follicular plugging that obstructs the apocrine gland ducts and perifolliculitis around the ducts. This is followed by rupture of the follicular epithelium, bacterial infection and formation of sinus tracts between abscesses under the skin, all which lead to the characteristic symptoms and signs of hidradenitis suppurativa.
The following are thought to play a role in the development of hidradenitis suppurativa.
Genetics -- frequently reported cases of hidradenitis suppurativa affecting multiple members of a family
Sex hormones -- apocrine sweat glands are stimulated by androgen and suppressed by oestrogen (exact role these hormones play remains controversial)
Endocrine factors -- obesity, hirsutism and acne are common findings among women with hidradenitis suppurativa
Cigarette smoking -- hidradenitis suppurativa appears to occur more frequently in smokers than non-smokers
Women are affected by hidradenitis suppurativa three times as often as men; the reason for this is unknown. The condition most commonly occurs between 20-40 years and coincides with the post-pubertal increase in androgen levels. Disease onset rarely occurs before puberty and after menopause.
What are the signs and symptoms of hidradenitis suppurativa?
The extent and severity of the disorder varies widely between individuals. Initially a firm pea-sized nodule (0.5-1.5 cm diameter) resembling acne may appear on one site. These lesions may resolve spontaneously or within hours to days rupture and ooze a pus-like discharge. These may heal without treatment but at a later time new lesions recur in the adjacent area. If uncontrolled, this leads to development of larger lesions (golf ball size), sinus tract formation, and involvement of multiple sites. Three distinct clinical stages have been defined for the condition.
Stage 1 -- solitary or multiple, isolated abscess formation without scarring or sinus tracts
Stage 2 -- recurrent abscesses, single or multiple widely separated lesions, with sinus tract formation
Stage 3 -- diffuse or broad involvement, with multiple interconnected sinus tracts and abscesses.
Disease may spread to involve less commonly associated sites including the nape of the neck, waistband and inner thighs. Anogenital involvement most commonly affects the groin, mons pubis, vulva, sides of the scrotum, perineum, buttocks and perianal folds. The abscesses and sinus tracts can be painful.