Pilonidal sinus and Pilonidal cyst are collectively referred to as Pilonidal disese. It is a chronic sinus or cyst in the soft tissue of the intergluteal fissure of the sacrococcygeal region and is characterized by the presence of hairs. History of pilonidal disese: Pilonidal disese means “nest of hair” and is derived from the Latin words pilus and nidus, a term coined by Herbert Mayo in 1830 and described by R.M. Hodges in 1880 as “pilonidal cyst”. More than 8,000 U.S. soldiers were hospitalized for this disease during World War II. It is mostly caused by prolonged jeep rides. Also known as “jeep seat or “Jeep riders’ disease”. Etiology: I. Congenital: Inclusion of skin due to residual medullary canal or developmental malformation of sacrococcygeal suture. II. Acquired: Sinuses and cysts are thought to be granulomatous diseases due to injury, surgery, foreign body irritation and chronic infection. Most confirm that hairs entering from outside are the main etiology. The process of formation of Tibetan hair sinus and Tibetan hair cysts Prevalent age and location: Mostly seen in young people aged 15-24 years old, except often in the sacrococcygeal region, rarely in the umbilicus, axilla and other places. Some patients are asymptomatic. Clinical manifestations Usually the main and first symptom is an acute abscess in the sacrococcygeal region with acute inflammatory features such as local redness, swelling, heat and pain. Tibetan hair cysts are often asymptomatic if there is no secondary infection, just a protrusion in the sacrococcygeal area, and some feel pain and swelling in the sacrococcygeal area. In the quiescent stage, small irregular holes with a diameter of about 1mm to 1cm are visible at the midline skin of sacrococcygeal area. the surrounding skin is red and hardened, often with scarring, and some hairs are visible. Treatment: 1.Excision of one-stage suture surgery to remove all diseased tissues, free muscle and skin, and completely suture the wound to make one-stage healing. It is suitable for cysts and small uninfected sinus tracts on the midline. 2.Excisional partial suture Excision of diseased tissue, skin on both sides of the wound and suture of sacral fascia, so that the majority of the wound heals in one stage and the middle part of the wound is healed by granulation tissue. It is suitable for cases with many sinus openings and sinus tracts, and the effect is the same as excisional one-stage suture, but the healing time is longer. 3.Excisional wound open secondary suture Suitable for cases with severe infection and cases with infected wound incision and drainage occurring in the first stage of suture. 4.Open excisional wound is suitable for cases in which the wound is too large to be sutured and the surgery is recurrent. Non-surgical treatment 1.Sacrococcygeal fossa does not need to be treated because there is only a depression in the sacrococcygeal joint, the lower part of the sacrum and the tip of the coccyx, without any symptoms and of no clinical importance. 2.Sacrococcygeal fossa and sacrococcygeal swelling should be treated with anti-inflammatory treatment if infection occurs, keep local cleanliness, and incision and drainage should be performed if abscess is reproduced. 3.Sclerotherapy by sclerotherapy injection. Postoperative picture