Thyroglossal duct cyst

Brief introduction of thyroglossal cyst Thyroglossal cyst (thyroglossal cyst) refers to a congenital cyst formed in the neck during the early development of the thyroid gland during the early development of the thyroid gland. There is often accumulation of epithelial secretions in the cyst. The cyst can communicate with the oral cavity through the blind hole of the tongue. In the case of secondary infection, the cyst can be broken to form the thyroglossal fistula. basic knowledge The proportion of illness: 0.012% Susceptible people: good for children and adolescents Mode of infection: non-infectious Complications: abscess

Causes of thyroglossal cyst

(1) Causes of the disease

The normal thyroglossal tube is located in front of the hyoid bone. The diameter of the tube is 1 to 2 mm. It is closely connected to the front of the hyoid bone and cannot be separated. It occurs at the 4th week of the embryo, and the median line of the original pharyngeal wall is equivalent to the 2nd and 3rd pairs. On the plane of the bow, the epithelial cells proliferate, forming a blind tube extending to the caudal side, the thyroid primordial, called the thyroglossal duct, which descends along the midline of the neck until the front of the trachea in the future, and the end is swollen to the sides. The left and right lateral lobes of the thyroid are formed. Under normal conditions, the thyroglossal duct begins to shrink and degenerate at the 6th week of the embryo. After the upper segment of the thyroglossal duct disappears, the opening of the initial segment still has a shallow concave, called blindness. Hole, if for some reason, the thyroglossal tube does not disappear or degenerate after the 10th week, the residual tubular structure can accumulate in the epithelial secretion to form a cyst, which is a thyroglossal cyst, which can be secondary to infection and formation of sputum. , is a thyroglossal sputum tube, there are three forms of fistula: complete fistula, from the blind hole to the neck outside the skin; inner blind tube, open in the blind hole; outer blind tube, open to the neck skin

(two) pathogenesis

The thyroglossal cyst occurs in the midline of the neck and can occur anywhere in the tongue to the sternal notch, but is most common near the hyoid bone. It is mostly located between the thyroid and the hyoid bone. There are many cysts above the plane of the hyoid bone. Located in the midline, below the plane of the hyoid bone can be centered or biased to one side, to the left, the thyroglossal cyst often has a complete capsule, the capsule wall is thin, the outer is fibrous tissue, and the inner lining is pseudo-stratified. Epithelial cells such as ciliated epithelium, squamous epithelium, stratified squamous epithelium, and abundant lymphoid tissue in the epithelium. Infected patients may have inflammatory cells: thyroid tissue may be present in the cyst wall, and the contents of the capsule are mostly mucoid or jelly. The sample contains protein, cholesterol, etc., and the disease can also develop cancer. In 1915, Ucherman first described the carcinogenesis of the thyroglossal cyst. More than 150 cases have been reported in the literature, most of which are papillary carcinoma and follicular carcinoma. , squamous cell carcinoma, etc., but there is still controversy about its source, some people think that occult thyroid cancer spread, and some people think that it originated from the ectopic thyroid tissue in the wall of the thyroglossal cyst.

Prevention of thyroglossal cyst

1. Recurrence after surgery

The thyroglossal cyst can have a certain recurrence rate after surgical resection. The recurrence rate of Sistrunk surgery is 3% to 5%, but the recurrence rate is as high as 26.9%. The recurrence rate of recurrence after surgery was up to 33%.

2. There is a possibility of cancer

In 1915, Ucherman first described the carcinogenesis of the thyroglossal cyst. More than 150 cases have been reported in the literature, most of which are papillary carcinoma, follicular carcinoma and squamous cell carcinoma. However, there are still controversies about its source. Some people think that it is the spread of occult thyroid cancer. Some people think that it originates from the ectopic thyroid tissue in the wall of the thyroglossal cyst.

Complication of thyroglossal cyst Complications

Cysts can pass through the tongue blind hole and communicate with the oral cavity, secondary infection, self-destruction, or misdiagnosis of abscess after incision and drainage, the formation of thyroglossal fistula, can also be seen after birth.

Symptoms of thyroglossal cysts Common symptoms Painful pharynx foreign body purulent discharge pharyngeal paraesthesia growth slow fatigue

The disease is mostly male, which occurs in children and adolescents. About 50% of cases occur before the age of 20, and the majority of patients can see the mass of the neck before it can occur in the median line from the tongue to the sternal notch. Any part, but the upper and lower parts of the hyoid bone are the most common.

Cysts grow slowly, round shape may be associated with neck pain, swallowing discomfort, pharyngeal foreign body sensation and other local symptoms, combined infection may be a painful mass or abscess, if it has formed a sinus, sinus, sinus There are mucus or purulent secretions in the tract, and obvious infections may be accompanied by systemic symptoms such as fever and fatigue.

At the time of physical examination, the mass can be touched near the midline of the neck, the texture is soft, the diameter is 1~5cm, round or oval, the surface is smooth, the boundary is clear, no adhesion to the surface skin and surrounding tissues, elastic or fluctuating, located in the hyoid bone The following cysts, between the lingual body and the cyst, can be touched by the tough cord and the lingual body, which can move up and down with the movement of the tongue.

Examination of thyroglossal cyst

1. B-ultrasound B-ultrasound image of the thyroglossal cyst is characterized by a circular or elliptical liquid dark area with clear boundaries, mostly single cysts, a few visible thin-walled separations, followed by enhanced echoes and long duration. The boundary may be blurred when infected or accompanied by a number of floating spots in the liquid dark area. When the fistula is formed, it can detect the dim line structure and mass or hyoid bone from the shallow to deep center. Connected, B-ultrasound diagnosis of thyroglossal cysts can be as accurate as 94%.

2. CT examination can understand the nature of the mass. The thyroglossal cyst is mostly a cystic mass in the middle of the neck from the tongue blind hole to the sternal jugular vein notch, with a complete capsule and a cyst wall. Thin, the density of the contents of the capsule is low, and the wall of the capsule can be thickened and thickened when infected, and the characteristic density of the thyroid tissue can be seen in the wall of some patients (about 30%).

3. Radionuclide imaging is also helpful for the diagnosis of this disease. The 131I or 99mTc scan can assess the size of the tumor, understand the presence or absence of active thyroid tissue, and facilitate the identification of thyroid mass.

4. X-ray examination of the neck, esophageal esophagography is helpful for diagnosis.

5. Iodine oil angiography can identify the fistula of the thyroglossal cyst.

Diagnosis and differentiation of thyroglossal cyst

The thyroglossal cyst can be moved according to the part of the neck before the neck and the tongue. The puncture can extract transparent, slightly turbid yellow thin or viscous liquid to make a preliminary diagnosis. The imaging examination can help to further confirm the diagnosis. Great meaning.

Differential diagnosis

1. Differential diagnosis of thyroglossal cyst

(1) underarm axillary lymphadenitis and lymphatic tuberculosis: manifested as axillary mass, lymphatic tuberculosis can also form a fistula long-term unhealed, but lymph node lesions are superficial, mostly a mass tumor, often tenderness, Identification by medical history and biopsy.

(2) ectopic thyroid: ectopic thyroid gland and thyroglossal cyst are both congenital abnormalities of the thyroid gland, which are closely related to embryonic development. The ectopic thyroid gland is often located in the pharynx of the base of the tongue or the blind hole of the tongue, showing a tumor-like protrusion. The surface is purple-blue, the texture is soft, the boundary is clear, and the ectopic thyroid of the tongue is mainly located in the front of the neck. The patient often has unclear language. In severe cases, swallowing may occur, and breathing is difficult. Because 75% of the ectopic thyroid is the only function. Thyroid tissue, the wrong removal of it will lead to serious consequences of life-long hypothyroidism, clinical attention should be paid to the identification of both, radionuclide scanning is the most effective identification method, when using 131I or 99mTc scanning, the ectopic thyroid gland is visible. Concentrated nuclide or no thyroid in the neck.

(3) Parathymus: not connected with the hyoid bone, the mass does not move up and down with swallowing, B-ultrasound is a substantial mass and can be differentiated from the thyroglossal cyst.

(4) Dermoid cyst: often manifested as a subgingival mass, can also be located in the sternal concave, generally cystic capsule thicker, no undulation, sensation of the face, often adhesion to the skin, not with swallowing and tongue movement, Puncture and extraction of sebaceous samples can be identified.

(5) thyroid adenoma: the disease is mostly characterized by a painless mass in the anterior cervical region, soft, clear boundary, with swallowing activity, but does not follow the tongue movement, can be identified by radionuclide scanning.

(6) cleft palate cyst: mostly located in the trigone of the carotid artery, the mass is mostly deviated from the midline, and has nothing to do with the hyoid bone. The puncture contains skin attachment and cholesterol crystal. It needs to be pathologically identified. During the operation, the fistula is crossed by the internal and external carotid artery. Pharynx.

(7) Other neck masses: such as thyroid cone, cystic hydroma, lipoma, sebaceous cyst, sublingual cyst, laryngeal cyst, parathyroid cyst and teratoma, etc. Identification of parts and traits.

2. Differential diagnosis of thyroglossal fistula

(1) tuberculous hernia in the neck: mostly caused by the spread of mediastinal tuberculous lymphadenitis. The fistula is mostly located in the upper sternal fossa. There was a history of ulceration and discharge of cheese-like substance, and lung X-ray examination showed tuberculosis. Strong positive PPD, etc. can be identified.

(2) : The disease is located in the anterior border of the sternocleidomastoid muscle. Sometimes, after the birth, there is a clear water sample in the pupil. The sacral canal extends to the carotid artery and is not connected to the hyoid bone. Inject the contrast agent into the X-ray examination to understand the direction of the fistula travel for identification.

(3) sacral neck median fissure: the disease is found after the birth of the hyoid bone to the thyroid cartilage under the skin, 3 ~ 5cm long, 2 ~ 5cm wide, the surface covered with red moist inner membrane, the distal end is a few millimeters of blindness The tube has a lentil-sized fibroid or fibrocartilage at the proximal end, and sometimes it can touch the ascending fibrous cord, which is fixed on both sides of the iliac nodules, so it is easy to identify with the thyroid gland.

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