Pilonidal Disease

Overview

Pilonidal disease affects the skin in the crease at the top of the buttocks, near the tailbone. A small pit, tunnel, or cyst forms in this area and often traps hair and skin debris. The word pilonidal comes from Latin words meaning nest of hair, reflecting the hair that is frequently found inside.

Many people have a pilonidal pit that causes no trouble. Problems arise when the area becomes infected, forming a painful, swollen abscess that may drain fluid or pus. Pilonidal disease is most common in young adults, particularly men, and tends to recur, so treatment focuses both on dealing with infection and on preventing it from coming back.

Symptoms

Symptoms range from a painless dimple to a painful infection:

• A small pit or dimple in the skin near the top of the buttock crease
• Pain, swelling, and redness when infected
• A tender lump that may feel warm
• Drainage of pus or blood, sometimes with an unpleasant odor
• Fever if the infection spreads

Some people have only occasional flare-ups, while others have repeated infections or persistent draining tunnels.

Causes

Pilonidal disease is thought to develop when loose hairs and friction lead to a problem in the skin of the buttock crease:

• Hair penetration: Loose hairs work their way into the skin, where the body reacts to them as foreign material.
• Friction and pressure: Prolonged sitting, tight clothing, and movement in the area contribute.
• Blocked hair follicles: Clogging and irritation can start the process.

Once a tunnel forms and traps hair and debris, it can easily become infected.

Risk Factors

• Being a young adult, especially male
• Having thick or coarse body hair
• Prolonged sitting, such as long-distance driving or desk work
• Being overweight
• Excess sweating and friction in the area
• A deep buttock cleft or family history of the condition

Diagnosis

Pilonidal disease is usually diagnosed by examining the area. A doctor looks for the characteristic pit or pits near the tailbone and any signs of infection such as redness, swelling, tenderness, or drainage. The diagnosis is typically clear from this examination alone, and special tests are rarely needed.

In complex or repeatedly recurring cases, imaging may occasionally be used to map the tunnels (sinus tracts) under the skin and guide surgical planning. The doctor may also ask about previous flare-ups, how often they occur, and any treatments tried before, since this helps decide between simple drainage and more definitive surgery.

Treatment

Treatment depends on whether there is an active infection and how often problems recur:

• Draining an abscess: An infected, swollen pilonidal abscess is usually treated by making a small incision to drain the pus, which quickly relieves pain.
• Antibiotics: Sometimes used when infection spreads to surrounding skin.
• Surgery: For recurrent or chronic disease, an operation removes the affected tissue and tunnels; several techniques exist, and wound care afterward is important.
• Hair removal: Keeping the area free of hair helps prevent recurrence.

Self-Care and Prevention

• Keep the area clean and dry
• Remove or trim hair in the buttock crease as advised
• Avoid prolonged sitting when possible and take breaks to stand
• Maintain a healthy weight
• Wear loose, breathable clothing

When to See a Doctor

See a doctor if you have pain, swelling, redness, or drainage near the top of the buttock crease, or a recurring lump in that area. Seek prompt medical care if you develop a fever, spreading redness, or increasing pain, which suggest the infection is worsening and may need urgent drainage and treatment. People with diabetes or a weakened immune system should seek care early, as infections can spread more quickly.

Related Topics

Frequently Asked Questions

References

1. American Society of Colon and Rectal Surgeons. Pilonidal disease.
2. Mayo Clinic. Pilonidal cyst — Symptoms and causes.
3. MedlinePlus, U.S. National Library of Medicine. Pilonidal cyst.
4. National Health Service (NHS). Pilonidal sinus.