Pilonidal disease (also called pilonidal abscess, pilonidal sinus) is an infection of the skin in the region between the 2 buttocks. It occurs when body area in the area breaks off and gets embedded into the skin. It is more common in men and those with a lot of thick, stiff body hair.
A pilonidal abscess may just be like a small pimple near to the buttock cleft. It may also be a large painful area
under the skin. This may discharge some clear liquid, blood or pus. When the pus is trapped within, the area becomes
swollen, red and painful. There may also be fever.
Most times, the pain and swelling would settle after the pus is discharged. In some, it settles after a course of antibiotics.
However, as there are hairs trapped below the skin, the infection is never fully cleared and it develops into a
pilonidal sinus. There may be one or more small little openings on the skin leading into the cavity below that
contains the hairs.
Some patients get repeated infections and inflammation of these sinus tracts, resulting in episodes of swelling, pain, and discharge of pus. Some of these tracts may extend deep towards the bone below.