Hidradenitis suppurativa, also known as acne inversa, is a chronic skin disease characterized by recurrent boil-like lumps (nodules) under the skin. The nodules become inflamed and painful. They tend to break open (rupture), causing abscesses that drain fluid and pus. As the abscesses heal, they produce significant scarring of the skin.

In most cases, the cause of hidradenitis suppurativa is unknown. The condition probably results from a combination of genetic and environmental factors. Originally, researchers believed that the disorder was caused by the blockage (occlusion) of specialized sweat glands called apocrine glands. However, recent studies have shown that the condition actually begins with a blockage of hair follicles in areas of the body that also contain a high concentration of apocrine glands (such as the armpits and groin). The hair follicles have a buildup of a fibrous protein called keratin (hyperkeratosis). The blocked hair follicles trap bacteria, leading to inflammation and rupture. Researchers have several ideas about what initially causes the follicles to become blocked and why the nodules tend to recur, but the causes remain unclear.

Hidradenitis suppurativa was once thought to be a rare condition because only the most severe cases were reported. However, recent studies have shown that the condition affects at least 1 in 100 people when milder cases are also considered. For reasons that are unclear, women are more commonly affected than men.

Hidradenitis suppurativa has been reported to run in families. Studies have found that 30 to 40 percent of affected individuals have at least one family member with the disorder. However, this finding may be an underestimate because affected individuals do not always tell their family members that they have the condition, and hidradenitis suppurativa is sometimes misdiagnosed as other skin disorders.

Published Date: October 27, 2021
Published By: National Institutes of Health