Pilonidal dimple is a small pit or sinus in the sacral area at the very top of the crease between the buttocks.

The majority of pilonidal dimples are harmless, congenital anomalies that consist of a small depression or pit. There may be increased hairiness around the area.

The pilonidal dimple may also be a deep tract, rather than a shallow depression, leading to a sinus that may contain hair. These can become infected and drain. On rare occasions, the sinus may extend into the spinal cord.

During adolescence, the pilonidal dimple or tract may become infected, forming a cyst-like structure called a pilonidal cyst. These may require surgical drainage or total excision to prevent reinfection.

• Congenital pilonidal dimple
• Congenital dermal sinus (of which the dimple is the mildest form)

Keep pilonidal dimples clean and free of debris during regular bathing. Report any drainage of fluid from the dimple, either clear or containing pus, to your health care provider.

• You note swelling, redness, drainage or tenderness around the pilonidal dimple.

The medical history will be obtained and a physical examination performed. In the vast majority of cases, the examining physician will merely comment that your infant or child has a pilonidal dimple and that you should not worry. On the rare occasion (when other findings may be associated), you may be asked the following information:

Medical history questions documenting pilonidal dimple in detail may include:

• Has there been any change in the appearance of the pilonidal dimple?
• Has there been any drainage from the dimple?
• Are any other symptoms developing?
• What other symptoms are also present?
• Is there any numbness or loss of movement in the legs?
• Has there been any change in bladder control?

If the lesion is an infected pilonidal cyst, surgery to remove the cyst may be recommended. Studies may be done to determine if the sinus extends into the spinal cord.