Hair retention sinus and hair retention cysts

　　The causes of hair retention sinus and hair retention cysts are unknown, but in the academic community, there are generally two theories.

　　First, congenital

　　Skin inclusions are caused by residual medullary ducts or developmental anomalies of the sacrococcygeal suture, but the precursors of hair retention disease are rarely found in the postanal shallow凹 of the median line of infants, while they are more common in adults.

　　Second, acquired

　　It is believed that sinus and cysts are granulomatous diseases caused by injury, surgery, foreign body stimulation, and chronic infection. Recently, it has been confirmed that hair entering from the external layer is the main cause. The intergluteal cleft has a negative attractive effect, which can cause hair to penetrate into the subcutaneous tissue. Excessive and long hair within the cleft has a filtering and softening effect on the hair skin, and the hair can penetrate the skin to form a short channel, which later deepens into a sinus. The hair shaft can also penetrate into the sinus when the hair root falls off. Changes in movement can be seen during the onset of the disease. However, only half of the cases can find hair, and this disease is more common in patients with excessive body hair, hyperactive sebaceous glands, deep intergluteal clefts, and those who often suffer injuries in the buttocks. The skin at the lower end of the sacrum of truck drivers is often subjected to long-term jarring, which can cause sebaceous gland tissue and debris to accumulate in the cyst, causing inflammation. The U.S. Army has a high incidence of this disease, known as the Jeep disease. Common pathogens include anaerobic bacteria, staphylococcus, streptococcus, and Escherichia coli.

　　Pilonidal sinus and pilonidal cyst are chronic sinus or cysts in the soft tissue of the intergluteal cleft of the sacrum, characterized by the retention of hair. They can also manifest as acute abscesses at the sacral tail, forming chronic sinus after rupture, or temporarily healing and then rupturing again, which can occur repeatedly. The cysts are often accompanied by granulation tissue, fibrosis, and usually contain a cluster of hair.

　　The main diagnostic signs of pilonidal sinus and pilonidal cyst are acute abscesses at the sacral tail or chronic sinus with secretion, with local acute inflammatory manifestations. The pilonidal sinus can be easily diagnosed by symptoms and signs when examined at the midline.

　　Pilonidal cysts usually have no symptoms unless there is secondary infection, just a bulge at the sacral tail, and some may feel pain and swelling in the sacral tail. Usually, the main symptom is the occurrence of an acute abscess at the sacral tail, with local redness, swelling, heat, and pain, which are characteristics of acute inflammation. Most of them can break through and discharge pus spontaneously or after surgical drainage, and the inflammation subsides. A few drainage orifices can completely close, but most are manifested as recurrent attacks or frequent discharge, forming sinus or fistula.

　　During the quiescent phase of pilonidal sinus, an irregular small hole about 1mm to 1cm in diameter can be seen at the midline skin of the sacrum, with the surrounding skin red, swollen, and hardened, often with scars. Some may have hair, and the probe can be inserted 3 to 4mm, and some can be inserted up to 10cm. When pressed, thin, foul-smelling fluid can be discharged. During the acute attack phase, there are acute inflammatory manifestations, with tenderness and swelling, and more purulent secretions are discharged. Sometimes abscesses and cellulitis occur.

　　The most critical care for pilonidal sinus and pilonidal cyst is still cleanliness. If not cleaned in time, the keratin produced by metabolism will block the hair follicles, causing them to fail to function normally, and thus the surrounding skin will become inflamed.

　　The main focus is on skin cleanliness, enhancing the body's resistance, preventing trauma, and actively treating pruritic skin diseases and systemic chronic diseases. The treatment or control of folliculitis should follow the principle of local disinfection, inflammation, and drying. Mild patients can use external anti-inflammatory drugs, sulfurated water, and other medications, while severe patients can take oral medications.

　　During the examination, the pilonidal sinus and pilonidal cyst can be seen at the midline, and they can be easily diagnosed by symptoms and signs.

　　1. Bacterial culture, most aerobic bacteria are Gram-negative bacteria.

　　2. Histopathology, the cyst wall is usually located below the reticular layer of the dermis. The cyst wall is composed of 3 to 4 layers of thick keratinocytes, which rapidly keratinize to form a dense homogeneous keratin without granular layer. The characteristic of hair cysts is the obvious lack of intercellular bridges between keratinocytes and the surrounding reticular nuclei. The cyst contents are composed of homogenized eosinophilic substances. Occasionally, cholesterol clefts can be seen in the keratin. About 1/4 of hair cysts can be calcified. When the cyst wall ruptures, it can cause foreign body reactions, and the cyst wall may partially or completely disintegrate later.

　　In addition to traditional Chinese and Western medicine treatment, attention should also be paid to diet in the case of pilonidal sinus and pilonidal cysts:

　　1. Eat more vegetables and fruits to increase vitamins and keep the bowels regular. The treatment or control of folliculitis should be based on the principles of sterilization, inflammation, and drying locally. Mild patients can use external anti-inflammatory drugs, sulfurated water, and other medications. Severe patients can take oral medications.

　　2. Spicy foods promote blood circulation and increase dampness and heat in the body. People with boils and carbuncles often have damp and hot constitutions. Spicy foods can add fuel to the fire after entering the mouth, causing inflammation to spread. It is forbidden to eat chili, chili oil, curry, Sichuan pepper, chive, garlic sprout, mustard, and other spicy foods.

　　For patients with pilonidal sinus and pilonidal cysts with mild symptoms, non-surgical therapy is the first choice.

　　The sacrococcygeal sinus does not require treatment because there is only a depression at the sacrococcygeal joint, the lower part of the sacrum, and the tip of the coccyx, without any symptoms, and has no clinical significance.

　　If the sacrococcygeal sinus or sacrococcygeal swelling occurs and infection occurs, anti-inflammatory treatment should be performed to keep the local area clean. If an abscess recurs, it should be incised and drained. However, the skin and subcutaneous tissue of the sacrococcygeal area are thick and hard, and there are no obvious symptoms in the early stage. Inflammation often spreads to surrounding tissues, causing cellulitis. Deep tissue necrosis should be incised and drained early.

　　Sclerosis therapy involves injecting corrosive drugs into the sinus, destroying the epithelium within the sinus and cyst, causing the cavity and sinus to close. Some people use phenol solution injection therapy, but there are not many users because pure phenol solution is used, which causes severe pain. Later, it was changed to an 80% concentration and performed under general anesthesia, injecting a gelatinous substance into the sinus to protect the surrounding skin. 1 to 5 ml of 80% phenol solution is slowly injected into the sinus, taking about 15 minutes. Slow injection can prevent complications such as skin burns, fat necrosis, or severe pain. This method can be repeated every 4 to 6 weeks.