Pilonidal Disease

What is pilonidal disease?

Pilonidal disease is a chronic infection of the skin in the area between the buttocks. Pilonidal, pronounced pie-luh-NIE-dul, occurs when hair follicles become plugged. It is a common condition that can happen to anyone but is most prevalent among teenagers and young adults. Boys are more likely than girls to have pilonidal disease. 

Pilonidal "Cyst"

Illustration: A Pilonidal "Cyst"

A child who has had pilonidal disease has a 50 percent chance of having it again in the future. Taking steps to keep the area clean and dry and avoiding long periods of sitting can help prevent a reoccurrence.

What are the symptoms of pilonidal disease?

The first symptom of pilonidal disease is typically pain, especially when sitting. The degree of pain varies from person to person. Some people may experience a small degree of a pain when sitting, while others will be in severe pain. 

Pilonidal disease often appears as a lump or swollen area that hurts when pressed with a finger. Pus or blood may or may not be draining from the lump. In some cases, a child may have a lump with some drainage and no pain. If the area becomes infected, the pus will be foul smelling and the area around it may become red and tender. 

Seek medical attention right away if symptoms include nausea, fever and exhaustion. 

What causes pilonidal disease?

Pilonidal disease is caused by plugged hair follicles in the crease between the buttocks. Any type of hair can cause problems, but the most troublesome is coarse, thick hair. The plugged follicles may rupture into the deeper skin, creating an indentation, or pit, in the skin. If irritation under the skin continues, a pilonidal sinus, or tract may form. This allows hair and other debris to travel under the skin and form a nest (a nidus), usually above the pit. This collection of hair and debris can get infected and an abscess may form. In severe pilonidals it is not unusual to have more than one abscess.

Factors that increase the risk of the follicles becoming plugged and rupturing include:

  • family history of pilonidal disease
  • sitting for a long time
  • activities such as horseback riding or bicycling that put extended pressure on the area
  • thick or coarse body hair
  • tight clothing
  • excess weight
  • tendency to sweat heavily 

How we care for pilonidal disease

The Pilonidal Care Program at Boston Children’s Hospital treats children and teenagers with pilonidal disease. As part of the Department of Surgery, we specialize in treating pilonidal disease and preventing its reoccurrence.