Hidradenitis suppurativa (HS), also known as acne inversa, is a long-term auto-inflammatory disease characterized by the occurrence of inflamed and swollen lumps.[2][3] These are typically painful and break open, releasing fluid or pus.[3] The areas most commonly affected are the underarms, under the breasts, and the groin.[1] Scar tissue remains after healing.[1]

The exact cause is usually unclear but believed to involve a combination of genetic and environmental factors.[3] About a third of people with the disease have an affected family member.[3] Other risk factors include obesity and smoking.[3] The condition is not caused by an infection, poor hygiene, or the use of deodorant.[3][4] Instead, it is believed to be caused by hair follicles that are near apocrine sweat glands being blocked, which in turn causes inflammation in the sweat glands.[1][3] Diagnosis is based on the symptoms.[2]

There is no known cure.[4] Warm baths may be tried in those with mild disease.[4] Cutting open the lesions to allow them to drain does not result in significant benefit.[2] While antibiotics are commonly used, evidence for their use is poor.[4] Immunosuppressive medication may also be tried.[2] In those with more severe disease, laser therapy or surgery to remove the affected skin may be carried out.[2] Rarely, a skin lesion may develop into skin cancer.[3]

If mild cases of HS are included, then the estimate of its frequency is from one to four percent of the population.[2][3] Women are three times more likely to be diagnosed with it than men.[2] Onset is typically in young adulthood and may become less common after fifty years old.[2] It was first described some time between 1833 and 1839 by French anatomist Alfred Velpeau.[1][5]