Intrathoracic goiter

Introduction to intrathoracic goiter Thyroid tumors are most common in endocrine gland tumors and are easily found in the neck. Intrathoracic goiter is a posterior sternal or mediastinal simple goiter or thyroid tumor. Because it is located behind the sternum or in the mediastinum, it is difficult to be found, which brings certain difficulties to diagnosis and treatment. Intrathoracic goiter is the same as cervical goiter. It is a nodular non-toxic benign thyroid tumor, sometimes the benign and malignant tumor, and the tumor and nodular hyperplasia are difficult to determine before surgery, even in pathological tissue. It is also very controversial in school. basic knowledge Sickness ratio: 0.0002%-0.0005% Susceptible people: no specific population Mode of infection: non-infectious Complications: recurrent laryngeal nerve injury

Cause of intrathoracic goiter

The disease includes pseudothoracic thyroid tumor and true intrathoracic thyroid tumor. The pseudothoracic thyroid tumor is a cervical thyroid that extends in the thoracic cavity. The true intrathoracic thyroid tumor is congenital.

Neck goiter down (50%)

The posterior sternal goiter is located in the anterior mediastinum and is directly related to the thyroid gland of the neck. It is also known as the secondary retrosternal goiter, which is the vast majority of intrathoracic goiter. The cause of this is often the neck goiter, located between the two deep fascia of the neck, with anterior cervical muscle restriction on both sides. Due to the action of the thyroid gland itself, it gradually falls. Finally, it develops into the thoracic entrance, and is then attracted by the negative pressure in the thoracic cavity, so that the normal or swollen thyroid gland partially or completely falls into the posterior sternal space, so it can also be called a falling intrathoracic goiter, according to its fall. The degree of entry can be divided into partial or complete types. Most of the cases of intrathoracic goiter that are clinically seen are of this type, and their blood supply is mainly derived from the inferior thyroid artery and its branches. This type of goiter should have equal chances, but due to the anatomical position of the human body, the descending thyroid or tumor, on the left side should encounter the subclavian artery, the common carotid artery and the aortic arch, while on the right side there is only the innominate artery, the gap It is wider, so it is more common on the right side. The vast majority of the posterior sternum is located in the anterior superior mediastinum. When the tumor occurs in the lower pole and isthmus, it descends forward to the anterior superior mediastinum; in front of the recurrent laryngeal nerve, the inferior thyroid artery, the common carotid artery, the innominate artery, the subclavian sheath and the innominate vein, the right side of the superior vena cava . When the tumor occurs on the posterior side of the lateral lobe, it can descend to the posterior superior mediastinum, located behind the above tissue, in the azimuth vein, in the triangular region in front of the spine.

Congenital factors (35%)

The true intrathoracic goiter is the opposite of the sternal thyroid in the anterior mediastinum, and most of the intrathoracic thyroid is located in the visceral mediastinum. After entering the chest, it is located in the inner and rear of the large blood vessel and is close to the trachea. Such intrathoracic goiter is connected to the thyroid gland and only has blood vessels and fiber cords or no connection. Anyone who is not connected can also be called primary or vaginal intrathoracic goiter. It is the thyroid tissue that remains in the mediastinum during the embryonic period of the patient. Later, it develops into a thyroid tumor. The blood supply comes from the intrathoracic blood vessels. In the medial and posterior mediastinum, the lower mediastinum only accounts for 10% to 15%, and a few can approach the diaphragm level. The mass is closely related to the trachea, sometimes even behind the esophagus, but it is less common. Dahan et al (1989) reported that the posterior thyroid gland, about 86% after the trachea, is basically located on the right side of the trachea. 4% is located behind the esophagus, and 4% is located in the right front of the trachea, although it is from the left lobe of the thyroid gland, and 6% surrounds the trachea (also known as the "ring").

Intrathoracic goiter prevention

Actively treat the primary disease, prevent exposure to toxic and harmful physicochemical substances during pregnancy, and ensure the healthy development of the fetus. Once the disease is treated in time, early detection, early diagnosis and early treatment are the key to prevention.

Intrathoracic goiter complications Complications, recurrent laryngeal nerve injury

(1) Injury of the recurrent laryngeal nerve during surgery: Therefore, any incision during operation should be separated from the thyroid capsule as much as possible. For the treatment of cervical plexus anesthesia, it is necessary to have a dialogue with the patient during the operation to avoid recurrent laryngeal nerve injury.

(2) Postoperative hemorrhage, airway compression and asphyxia: The thyroid stump should be overlapped and sutured during operation, and the upper and lower thyroid artery ligation should be firmly secured. The surgical separation should be in the capsule as much as possible to prevent damage to the surrounding tissue and cause accidental tissue damage and bleeding. At the end of the operation, the vacuum suction was routinely placed in the wound, and the wound was oozing in time, and it was convenient to observe the presence or absence of active bleeding.

(3) Tracheal collapse or stenosis: a large falling intrathoracic goiter can compress the trachea for a long time, which can cause the trachea to be deformed and twisted. When the tracheal wall is softened, it should be sutured with the anterior cervical muscle. To prevent postoperative tracheal collapse or stenosis. If the symptoms of acute respiratory obstruction occur, tracheotomy should be performed to ensure the airway is unobstructed.

Symptoms of intrathoracic goiter. Common symptoms. Upper extremity edema, hoarseness, dysphagia, hunchback, difficulty breathing, suffocation, night sweats, urgency, high blood pressure, panic

The intrathoracic thyroid gland is more common in women, with a longer history. The main complaint is dyspnea. It is several years or ten years, and gradually worsens. At the same time, there is a neck mass. The lower edge of the thyroid gland is generally inaccessible. Some patients are often accompanied by different degrees of hunchback. The neck is short and obese, and some patients often have a history of thyroid surgery.

Asymptomatic cases account for about 30%, the clinical symptoms are mainly caused by the compression of surrounding organs by the mass, such as compression of the trachea caused by dyspnea, wheezing; compression of the superior vena cava caused by upper chest and neck superficial vein engorgement, upper extremity edema and other upper cavity Venous syndrome; compression of the esophagus causes difficulty in swallowing, but because the esophagus is softer than the trachea, even if the esophagus is compressed or displaced, it can easily avoid the pressure of the tumor, so the above symptoms are often rare, the severity of the symptoms and the size of the mass, Related to the site, the simple intrathoracic goiter is obviously enlarged, the compression symptoms appear, because the posterior sternal space is narrow, so the posterior sternal goiter, even if the tumor is not large, symptoms may appear in the early stage, individual patients are invaded in the thoracic cavity due to the mass At the entrance or spontaneous, traumatic hemorrhage causes acute dyspnea. In severe cases, due to long-term compression of the trachea, the tumor may soften or even cause suffocation. These symptoms may increase when lying on the back or head to the affected side. If there is hoarseness, Even the loss of sound, often caused by malignant tumor compression of the recurrent laryngeal nerve, benign intrathoracic goiter is very rare for recurrent laryngeal nerve compression Horner syndrome then decreased to mediastinal tumor compression caused by sympathetic, but rare, as accompanied by palpitation, shortness of breath, sweating, high blood pressure, is suggestive of the presence of hyperthyroidism.

Physical examination: Falling in-thoracic goiter can reach the enlarged thyroid gland in the neck and extend into the chest, often not touching the lower pole. Patients with a history of thyroid surgery and complete retrosternal goiter, neck It is difficult to touch the mass. The physical examination should pay attention to the relationship between the neck thyroid and the intrathoracic thyroid gland, the relationship between the tumor and the swallowing activity, and the condition of the lower boundary and the thyroid tumor extending to the chest.

Examination of intrathoracic goiter

When the blood picture is normal, when there is hyperthyroidism, serum T3, T4 may increase, and TSH may decrease.

1. Chest X-ray is preferred

(1) When the retrosternal goiter is small, the mediastinal shadow does not widen. At this time, if you look closely, you can see that the upper mediastinum density is slightly increased, and the trachea can often be compressed. The presence of the tumor can be estimated by the curved indentation of the trachea. When the tumor is enlarged, the upper mediastinum shadow can be widened to one or both sides. If the tumor occurs in the right lobe, the mediastinal shadow protrudes to the right side, and the larger one can protrude slightly to the left; if it occurs to the left Leaves, when the tumor is small, the shadow only protrudes to the left side. When the time is large, the shadow can protrude to the right side at the same time. If the tumor occurs on both sides or the isthmus, the mediastinal shadow protrudes to the sides, and the resistance of the aortic arch is relatively fixed. Large, so the mediastinal shadow mainly protrudes to the right side, while the enlarged thyroid can compress the aortic arch to the left and below.

(2) When the thyroid volume is large, the trachea can be compressed to shift to the opposite side and the rear side; at the rear of the trachea, the compressed trachea is displaced to the front and the opposite side; when the trachea is compressed on both sides, the scabbard-like deformation occurs. Generally, the trachea has a large curvature, which often extends to the neck and ends at the throat. This phenomenon is a strong evidence of goiter.

(3) The shadow of the retrosternal goiter is often connected with the soft tissue of the neck. On the fluoroscopy or X-ray film, the shadow of the upper mediastinum is often extended to the neck. According to this, it is often distinguished from other mediastinal tumors. The mass is often closely connected to the trachea and has an upward movement during swallowing, but without this movement, the possibility of the disease cannot be completely ruled out.

(4) The esophagus can also be displaced to the left or right side. Tumors can occasionally be inserted between the esophagus and the trachea, so that the distance between the two is widened. For example, the destruction of the esophageal mucosa is evidence of malignant tumors.

(5) The edge of benign thyroid tumor may be slightly lobulated, the malignant tumor is wavy, the shadow density of the tumor is uniform, and sometimes there may be calcification, often in the form of a block or a dot, which may be curved at the edge, but not with or without Calcification identifies the benign, malignant, malignant tumors that can metastasize to the lungs or bones.

(6) Mediastinal inhalation angiography can clearly show the thyroid tumor, and the transverse mass tomography can be used to find that the mass is located in front of the aorta.

2. CT examination: The situation of the mass can be understood in more detail. Typical signs are as follows:

1 It is continuous with the thyroid of the neck, located in the anterior space of the trachea, and can also extend into the trachea and the esophagus.

2 The boundary is clear.

3 with a bit shape, ring calcification.

4 The mass is mostly a substantial shadow, the density is uneven, accompanied by a low-density area that is not enhanced.

5 often accompanied by tracheal displacement, compression, esophageal compression and so on.

The 6CT value is higher than the surrounding muscle tissue, usually 50 ~ 70HU, sometimes up to 110 ~ 300HU, cystic area CT value of 15 ~ 35HU.

3. B-ultrasound, MRI and DSA: B-ultrasound can confirm that the mass is cystic or solid. MRI helps to understand the relationship between the mass and the surrounding large blood vessels, and eliminates the possibility of hemangioma. DSA helps to understand the blood supply of the mass and the blood of the mass itself. Loop situation.

4. Radionuclide 131I examination : can help determine whether the mass is thyroid tissue, but also determine its size, location or presence of thermal nodules secondary to hyperthyroidism.

Diagnosis and diagnosis of intrathoracic goiter

Diagnostic criteria

According to the medical history and clinical symptoms and signs, the isotope I131 scans the tumor for functional ectopic thyroid to confirm the diagnosis.

1. Intrathoracic goiter and tumors are more common in women. Carefully ask about the history and clinical manifestations; pay attention to understand whether the patient has disappeared from the neck mass in the past.

2. Clinical diagnosis mainly depends on CT and other auxiliary examinations.

Differential diagnosis

1. Identification of intrathoracic goiter with hemangioma If it protrudes to the right, it should be differentiated from the anonymous aneurysm and the odd vein; when it protrudes to the left mediastinum, it should be differentiated from the aortic aneurysm.

(1) Anonymous aneurysm has no upward movement when the patient performs swallowing action. The pulsation is sometimes seen under fluoroscopy. The phonogram is checked, and the pulsation is synchronized with the aortic wave. In some cases, the rib can be destroyed. If necessary, the artery should be performed. Contrast identification.

(2) The lung texture is still visible in the veins of the odd veins, and the azygous venous veins can be seen at the proximal hilar, and the trachea is not under pressure. If necessary, tracheal bronchography is used for identification.

(3) Aortic aneurysm often causes the aortic arch to rise and shift upward; while the retrosternal goiter causes the aortic arch to shift to the left. The aortic aneurysm is often accompanied by other parts of the aortic dilatation and heart enlargement. Record wave or aortic angiography, in addition, aortic aneurysm or anonymous aneurysm is more common with syphilis, such as Hua-Kang reaction positive, should be considered as aneurysm first.

2. Identifying intrathoracic goiter with neurogenic tumors, such as those located in the posterior superior mediastinum, should be differentiated from neurogenic tumors.

3. Identification of thymoma with thymoma is also located in the anterior mediastinum, but the position is lower than the intrathoracic goiter, often with myasthenia gravis, simple erythrocyte dysplasia, hypogammaglobulinemia and other tumor-bearing symptoms. Surgical resection of pathological diagnosis is required.

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