Pilonidal disease affects the natal cleft (the area between the buttocks above the anus). It occurs when hairs burrow beneath the skin causing a cavity that may become swollen and infected. This can result in pain, swelling and discharge. Sometimes an acute abscess develops; in other cases there is an opening (a pilonidal sinus) which discharges pus or bloodstained fluid.
Pilonidal disease affects teenagers and young adults. Surgery is recommended for patients who have repeated infection or other significant symptoms.