What are pilonidal cysts and sinuses? Skin condition caused by ingrown hairs.
A pilonidal cyst is a skin condition caused by ingrown hairs that tunnel into the skin between the buttocks. They often present as a lump at the top of the buttocks where infected fluid may drain. This is an inherited condition where hair tends to grow inward and tunnel under the skin, causing chronic inflammation and occasionally an infection. Sometimes, hair from the head can also be a culprit.