Pilonidal cyst

　　1. Congenital

　　Due to the residual medullary tube or developmental malformation of the sacrococcygeal suture, skin inclusions occur, but the precursors of hair follicle sinus disease are rarely found in the posterior shallow fossa of the infant's median line, but it is common in adults.

　　2. 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 shed hair to penetrate into the subcutaneous tissue. If the hair within the cleft is too long and too many, the hair top has a filtering and softening effect on the skin, and the hair can penetrate into the skin, forming a short path, which later deepens into a sinus. Hair roots that fall into the sinus can also cause the hair shaft to penetrate. During the course of the disease, changes in movement can be seen, but only half of the cases can find hair. This disease is more common in patients with excessive hair on the flat, excessive activity of sebaceous glands, a deep intergluteal cleft, and those who are often injured in the buttocks. The skin at the tail end of the driver's buttocks is often subjected to long-term shaking, injury, 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 Jeep disease. Common pathogens include anaerobic bacteria, staphylococci, streptococci, and Escherichia coli. Rainsbury and Southan analyzed the static condition of hair follicle sinus disease, and found that individual bacteria were less than half, while anaerobic bacteria accounted for 58%. Interestingly, staphylococci are not common, and most aerobic bacteria are Gram-negative bacteria.

　　Cancer occurring in the pilonidal sinus is rare. Phipshen (1981) reviewed the literature and found only 32 cases. The lesions are mostly well-differentiated squamous cell carcinoma. Changes in the wound should raise the suspicion of malignancy, such as easy-to-break ulcers, rapid growth, excoriations, and mold-like edges. Radical resection should be the first choice. Due to the widespread application of skin grafting or flap surgery for wounds, enlargement of the inguinal lymph nodes should be biopsied to exclude metastasis. If there is metastasis, the prognosis is poor. The literature reports a 5-year survival rate of 51%, and a recurrence rate of 50%. The incidence of metastasis in the inguinal lymph nodes at initial diagnosis is 14%.

　　Epidermoid cysts may be asymptomatic without secondary infection. Usually, the main symptom is the occurrence of an acute abscess at the sacral tail, similar to other soft tissue abscesses. Local symptoms include redness, swelling, heat, and pain, etc. The inflammation can usually be spontaneously broken through and discharge pus, or the inflammation can regress after surgical drainage. The drainage orifice can be completely closed, but most are manifested as recurrent attacks or frequent flowing to form a sinus or fistula.

　　The primary ducts are often located in the midline of the sacral tail, with the inner wall being squamous epithelium. The duct extends a certain distance under the skin, generally about 2-3 cm long, and may have small abscess cavities. Small branches may be divided from the primary duct, and the inner walls of the abscess cavities and branches are mostly granulation tissue. Hairs not connected with the surrounding skin often grow out from the sinus orifice. The pilonidal cavity is located in the midline, most呈 straight, about 1-15 cm long, with the cavity wall formed by tough fibrous tissue. Secondary ducts can branch from the main cavity to the subcutaneous tissue, often with secretion exuding onto the skin surface, extending from the lateral head to the side, and a few can also extend towards the anus, thus easily confusing with common perianal fistulas.

　　The main diagnostic signs of pilonidal sinus or cyst are acute abscess at the sacral tail or chronic sinus with secretion. Local symptoms include pain, tenderness, and inflammatory infiltration. The pilonidal cavity can be seen in the midline during examination.

　　1. Prevent infection, strengthen physical exercise, enhance physical fitness, improve the body's immune function, and live a regular life.

　　2. Maintaining a good attitude is very important. Keep a cheerful mood, have an optimistic and magnanimous spirit, and a strong confidence to overcome diseases. Do not fear, only in this way can one mobilize the subjective initiative of people and improve the immune function of the body.

　　3. Pay attention to skin hygiene, strengthen physical exercise, and enhance the skin's resistance.

　　The histopathological cyst is located in the dermis or subcutaneous tissue, with the cyst wall being epidermal. Hair shafts can be seen inside the cyst wall. Around the cyst, there is a mixed inflammatory cell infiltration of lymphocytes, tissue cells, and neutrophils, and foreign giant cells and granulation tissue can be seen.

　　What foods should not be eaten for epidermoid cysts?

　　Spicy foods have the effect of promoting blood circulation and enhancing internal damp-heat, and patients with boils and carbuncles often have a damp and hot constitution. After eating spicy foods, it will pour oil on the fire, causing the inflammation to spread. It is forbidden to eat spicy foods such as chili, chili oil, curry, Sichuan pepper, chive, garlic sprout, and mustard.

　　Surgical Treatment:

　　When an acute abscess forms, the treatment method is very simple, that is, to perform cross incision and drainage under local anesthesia, choosing the location with the most obvious fluctuation or tenderness, avoiding the median line. Antibiotics cannot replace surgical drainage. If the abscess is accompanied by cellulitis, or the patient has diabetes, cardiovascular disease, or immune deficiency, etc., antibiotic treatment can be added. Regularly check the wound after surgery to see if it is healing, shave the hair around, and gently probe the sinus cavity with a probe, or it may be possible to pull out a cluster of hair, which acts as a foreign body and causes the infection to persist. After the above treatment, some patients may heal the wound in one stage, but most still do not heal after 1 to 2 months, showing chronic recurrence, so radical surgical treatment for pilonidal sinus is needed.

　　For radical surgery for chronic pilonidal sinus, no method can be proven to be completely successful. In the past, extensive resection surgery has been used for treatment, and practice has shown that wound healing is slow, causing unnecessary pain and loss to patients. Currently, more conservative surgery is adopted, which only removes the diseased tissue while trying to preserve normal skin and subcutaneous tissue. The preferred method is the bag-shaped operation, which involves removing the superficial part of the sinus tract wall and the upper skin cover, suturing the residual cavity of the sinus tract with the skin incision margin, thereby reducing the wound size to promote healing. The lateral sinus tracts need to be cut separately to the end, and they are also bag-shaped, usually using catgut or absorbable artificial sutures. Careful postoperative management is very important and is often the key to the healing of open pilonidal sinus. Fine gauze dressings are filled in the sinus tract, and it is necessary to keep the wound edges apart, the flatter the better. Use a bandage to fix the dressing instead of adhesive tape to reduce skin irritation, pay attention to local hygiene, and if the wound is found to have a bridge, it should be separated immediately with a cotton swab. If there is too much hair around, it should be shaved regularly. Excessive granulation tissue growth can be scraped off or silver nitrate burned, and regular follow-up until the wound is completely healed. Occasionally, if the wound does not heal for a long time, it can be regularly scraped and washed with water to keep it clean. In some cases, the application of pressure dressing may promote wound healing.

　　For recurrent pilonidal sinus, it is not necessary to perform extensive resection. A bag-shaped operation similar to the original surgery can be performed, which is simple and equally effective.