There is a small dimple in the midline of the tail but no feeling

Introduction Hairy diseases rarely appear before infection occurs in the sinus. A typical case is a small pit in the midline of the tail without any sensation. There are fine holes in the pits, and some are difficult to penetrate with the lacrimal sac probe. This is the original sinus, 5 to 6 cm from the anus. A superficial abscess is formed locally after infection, and the pus is discharged after self-destruction or surgical incision. The abscess discharges a thin pus a few days later, leaving an induration. Another abscess can occur with bacterial infection again. If the sinus sinus is cancerous, the prognosis is poor if there is metastasis. The 5-year survival rate reported in the literature is 51%. The recurrence rate accounts for 50%. At the time of initial diagnosis, the inguinal lymph nodes were found to have a metastasis of 14%.

Cause

(1) Causes of the disease

There are many the causes of this disease, which can be roughly divided into two categories: developmental causes and injuries. In the second half of the 19th century, due to the development of embryology, specific lesions that occurred at specific sites of the disease were naturally suspected to be caused by developmental causes. There are roughly three hypotheses that summarize a large number of writings:

1. The dorsal sacral cystic residue theory: French scholar Tourneaux and Herrman proposed in 1887, until 1942, American scholar Kooistra still supported this.

2. The development of the central joint malformation in the appendix area: Fere (1878) proposed that the central joint deformity development in the appendix caused the formation of cysts in the skin. In 1935, Fox advocated this theory.

3. Degenerate remnants resembling the structure of the tail gland of birds: Stone proposed this theory in 1931. Some people think that it is a degenerate remnant of a certain gland. Until Patey et al. reported in 1946 that a hairdresser found a sinus on his finger, the hypothesis of congenital pathogens or developmental causes began to be suspected and sought to explain the cause of acquisition. There are quite a lot of such reports in the future. It is thought that the hair is implanted after the skin is damaged, or the hair is worn through the skin, causing infection and skin. Bearley believes that the sinus sinus is initially formed by the surrounding hair piercing the skin to form a short sinus, while the root of the hair is still connected to its hair follicle. When this hair falls off, it continues to be inhaled by the attraction generated by the sinus. He suggests a phase called "piercing sinus" in the first stage and a "inhalation sinus" in the second stage. This hypothesis seems to explain some of the clinical phenomena and historical facts that are already known. For example, the disease is mainly male, and it occurs mostly in people or races with many body hairs. The site of occurrence is a hairy area, and is a site that is often subjected to sputum and friction. Bearley said that the high incidence of jeep occupants is due to the fact that these soldiers are riding on low and hard jeep on long and bumpy roads, often twisting and rubbing their hips. He has measured changes in local pressure when the gluteal groove is opened. When the buttocks are separated to the sides, the partial pressure can suddenly drop 80mmH2O. Explain the attractiveness that this part can produce. At a seminar in 1975, Rod reported that one case had a hair removed from the sinus of the sinus, a total of 23 hairs, the color, thickness, length and direction of the hair were consistent. He believes that this is a continuous growth from a "young-type" hair follicle. The "young-type" hair follicle does not start functioning during the fetal period like the "head-type" hair follicle, but does not start functioning during the germination period. It takes about 3 to 6 months for each hair to grow to fall off. While the hair is still growing, the sinus is infected and the hair is exposed. He believes that it is difficult to accurately cut the hair follicles during the histological examination or that the hair follicle structure has been destroyed when cut, so the general pathological report always says that only the hair has no hair follicles. Rord's report shows that there are still many problems waiting to be explained in the traditional etiology.

(two) pathogenesis

The primary sinus in the dorsal midline of the tailbone is open to the skin, about 2 to 3 cm deep, with a small lumen at the end. The sinus contains hair, sometimes the hair sticks out at the sinus. The hair is completely free, and the ends are sharp and it is difficult to find the hair follicle. The secondary duct is located deep in the original sinus. After infection, it breaks into the skin and is rich in granulation tissue. The opening of the primary sinus is lined with squamous epithelium. This epithelial lining is about 2 mm deep inside the sinus and is replaced by granulation tissue. The secondary duct is located on the "cranial side" of the primary sinus.

an examination

Related inspection

Bone and joint MRI examination temperature perception

The disease rarely shows symptoms before infection occurs in the sinus. A typical case is a small pit in the midline of the tail without any sensation. There are fine holes in the pits, and some are difficult to penetrate with the lacrimal sac probe. This is the original sinus, 5 to 6 cm from the anus. A superficial abscess is formed locally after infection, and the pus is discharged after self-destruction or surgical incision. The abscess discharges a thin pus a few days later, leaving an induration. Another abscess can occur with bacterial infection again. The above symptoms are repeated. This recurs so that several sinus openings can occur locally. These sinus openings can be very close, and may also have a distance of 2 to 3 cm. Most sinus openings allow for fine probes to pass. The sinus is different in depth and can reach several centimeters. The secondary sinus is more above the "skull side" of the original sinus. It is often observed that it is slightly biased to one side, especially to the left. A "dry period" in the sinus area can be used to visualize a long elliptical induration or cystic mass.

Differential diagnosis

The sinus sinus is easily diagnosed by symptoms and signs, but should be differentiated from sputum, anal fistula and granuloma.

1.

Growing on the skin, protruding from the skin, the top is yellow. The sputum has multiple outer holes with necrotic tissue.

Anal fistula

The outer mouth of the anal fistula is close to the anus, the fistula is lined to the anus, the percussion has a cord, the anal canal has an internal mouth, and there is a history of anorectal abscess. The direction of the sinus sinus is mostly toward the cranial side, rarely down.

3. Other

Tuberculous granuloma is connected to the bone. X-ray examination shows that the bone is damaged, and other parts of the body have tuberculous lesions. Syphilitic granuloma has a history of syphilis. Syphilis seropositive.

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