Mediastinal teratoma

Introduction to mediastinal teratoma A teratoma is a true tumor composed of two different types of tissues with two or three germ layers. These tissues can be composed of mature, immature or mixed components with large teratomas in the mediastinum. Some are benign tumors, accounting for 70% of children with teratomas and 60% for adults. basic knowledge The proportion of illness: 0.0003%-0.0004% Susceptible people: no specific population Mode of infection: non-infectious Complications: cerebrospinal fluid leakage

The cause of mediastinal teratoma

(1) Causes of the disease

Embryonic development (37%):

The source of teratoma is thought to be caused by the pluripotent embryonic cells that are detached from the original formation. The cells are distributed in the yolk sac that travels along the hindgut to the genital tract and migrates to the primordial gonads. The midline and the midline, so teratomas can occur not only in the gonads but also in the retroperitoneal and mediastinum. Another explanation is that the mediastinal teratoma comes from the third cell population in the cleft palate and depression. Embryonic development It sinks into the chest with the cardiovascular system.

(two) pathogenesis

Although there are many pathological classifications of teratoma, the following classifications are generally used in China:

Mature teratoma (24%):

Mature teratoma is the most common germ cell tumor in the mediastinum, accounting for 9% to 20% of all thymic tumors. Most of them are located in the anterior mediastinum, occasionally in the posterior mediastinum, and there is no gender difference. The peak age of onset is 30 years old, but In recent years, there has been an increase in the incidence of this disease in men with Kleinfelt syndrome. Nearly one-third of patients with this disease have no clinical symptoms, but were found during routine chest X-ray examination.

The remaining cases may have chest and back pain, difficulty breathing, upper vena cava blockage syndrome, or cough and other symptoms. After the mature teratoma ruptures, the substance can flow into the bronchi to cause fatty pneumonia, such as these substances contain hair. Can also cause serious complications, about 25% of the mediastinal teratoma X-ray examination showed obvious calcification.

Macroscopic view, mature teratoma has an envelope, showing one or more large sacs, the tumor capsule is weak and smooth, can be milky white, gray or brownish yellow, smooth surface, often accompanied by microvascular network, occasional The maximum diameter of the pedicle is 10-11 cm. The tumor surface is mostly smooth or granular in the inner wall of the single-sac sac. It contains 1 to several papillary bulges. There are horny debris in the cyst, with or without hair. To the cartilage or bone.

Histologically, the most common components are the skin, including keratinized squamous epithelium and its appendages such as hair follicles, sebaceous glands and sweat glands, as well as epithelial and pancreatic tissues of the respiratory and digestive tract, interlobular tissue such as fibrous tissue and smooth muscle. As well as the cartilage and bone tissue mentioned above, less than 10% of mature teratomas contain teeth, choroid plexus, nerve tissue, bone marrow, skeletal muscle, kidney tissue or retinal tissue.

Microscopic examination showed various tissues derived from the 3 germ layers. The tissue differentiated and matured and differentiated towards the organ, but did not contain intact organs. 5% of mature teratomas may have malignant transformation. A few mediastinal mature teratomas have been reported. There are squamous cell carcinomas, adenocarcinomas or sarcomas. Without these concurrent components, mature teratoma can be treated surgically and the prognosis is good.

Immature teratoma (12%):

Immature teratoma is a rare malignant tumor, accounting for only 1% of mediastinal teratomas. It is also composed of embryonic neuroepithelial, mesenchymal tissue and epithelial components mixed in different proportions, in other parts, especially in the gonads. And the appendix, the number of primitive neuroepithelial tissues in the immature teratoma can be used as a prognostic indicator. In the immature teratoma in the mediastinum, age is the most important factor affecting the prognosis, occurring after the age of 75. Immature teratomas are invasive, and patients <15 years of age have no malignant progression after surgery alone because they are similar to the biological behavior of germ cells in the gonads, such as yolk sac tumors in infants and children. Sex is not as obvious as adults.

The naked eye: the gross view is larger, the cut surface is mainly based on the microcapsules, and more than half of the cases can be seen in the bone and calcification area. Skin, hair and sebum are less common.

Microscopic examination showed that 2 to 3 germ layer-derived tissues were mainly composed of immature (embryonic components) tissues; some could be all immature components, biological behaviors included benign, critical to malignant, and histomorphology from cancer To sarcoma, various components are closely doped, mutation distribution, lack of migration stage, common to primitive mesenchymal and/or primitive neural tissue, primitive mesenchymal tissue cells are small round or short fusiform, nuclear dense deep staining, The cytoplasm is sparse, or the cytoplasmic loose stellate cells are easily mistaken for fibrosarcoma or mucinous sarcoma. The primitive neural tissue is composed of primitive neuroepithelial structures, often accompanied by melanocytes and medullary cells or neuroblasts. The shape-like structure should be distinguished from the ependymal membrane and choroid plexus of mature nerve tissue. It should be noted that primitive neural tissue and immature mesenchymal tissue can often be mixed, and the under-mature tissue of each germ layer can be regarded as the immature to mature stage. process.

Mediastinal teratoma prevention

There is no effective preventive measure for this disease. Early detection and early diagnosis are the key to the prevention and treatment of this disease.

Mediastinal teratoma complications Complications cerebrospinal fluid leakage

Usually complicated by cerebrospinal fluid leakage.

Symptoms of mediastinal teratoma common symptoms pericardial dyspnea dyspnea tracheal space formation mass sound hoarseness pleural effusion chest pain

Patients with benign teratoma have no symptoms, even if the tumor is huge, there is no discomfort. Symptoms mainly include chest pain, cough and difficulty in breathing. Occasionally, the tumor ruptures into the tracheobronchial tree, and the contents of the capsule can cough up, often as bean dregs-like sebum. There are hair and teeth, tumor perforation of the pericardium can cause acute pericardial tamponade, rupture of the mediastinal pleura to cause pleural effusion, tumors will produce compression symptoms of surrounding tissues such as compression of the trachea and bronchus in addition to coughing and breathing difficulties are also prone to lungs Discomfort, pneumonia and other symptoms, tumor compression of the recurrent laryngeal nerve appears hoarseness, the tumor compression of the superior vena cava will appear in the superior vena cava syndrome.

Most of the malignant tumors will have different symptoms, still suffering from chest pain, cough and dyspnea. At the same time, weight loss and fever will occur. If the tumor grows rapidly, and the surrounding organs are invaded or metastasized, the corresponding symptoms and signs will appear.

Examination of mediastinal teratoma

Benign teratoma tumor markers are negative, but teratoma with malignant tissue components, especially teratoma with embryonic components, can be positive for tumor markers such as AFP, HCG, LDH, or CA19-9. And after the tumor resection, the titer of the above indicators decreases. If the leiomyosarcoma component is included, the myosin test may be positive, the tumor containing the nerve component is positive for S-100 protein, and the keratin staining positive indicates that the tumor cells contain adenocarcinoma and squamous cell carcinoma. Ingredients.

1. General X-ray examination

It can be found that generally only one side of the mediastinum protrudes, individual cases can be protruded to both sides, sometimes the tumor size varies greatly, the skin-like cyst is secondary infection, surrounded by inflammatory adhesions and pleural thickening, making the outline slightly irregular Teratoma presents a heterogeneous density due to its many different tissue structures. The density of sites with more adipose tissue is low, the wall of the cyst can be calcified, and the bone and tooth shadows are seen in the tumor. Performance, if the tumor is significantly increased in the short term should be considered malignant, and malignant tumors are more solid tumors.

2. CT scan

The characteristic manifestation is a mass with a fat density containing a calcified solid nodule, or a mass with a liquid portion, wherein the fat portion is above and the liquid portion is below, with a fat-liquid surface between them, at this interface It can be seen that the circular shadow of linear or cord-like mixed density is a hair mass. When the tumor has secondary infection, there is inflammatory adhesion and pleural thickening, and its contour is blurred. CT scan can roughly define the tumor size and its relationship with surrounding tissues. If the lesion is suspected to have metastasized, abdominal CT, brain CT and bone scan can provide a corresponding basis.

Diagnosis and diagnosis of mediastinal teratoma

Most of the teratoma are located in the anterior mediastinum, more in the middle of the anterior mediastinum, at the junction of the heart and the aortic arch. A few higher-positioned masses have an upper edge that passes over the top of the aortic arch, or a lower position, located in the lower part of the anterior mediastinum, occasionally located Posterior mediastinum, X-ray, CT examination showed that the bottom of the anterior mediastinum had a dense round, round or nodular shape. If bone or teeth were found to be diagnostic, the tumor was worn to the lungs or bronchi. The patient coughs up sebaceous gland secretions or hair and has a characteristic diagnostic value.

Differential diagnosis

1. Thymoma: is a tumor originating from the thymus. X-ray examination of the tumor is often round or oval, with sharp and sharp edges, or lobes, located at the base of the anterior superior mediastinum, close to the posterior side of the sternum, lateral position The chest radiograph has a lighter density and an unclear outline. At the sternal angle level, the predilection site is similar to a genital tumor, while the latter may be slightly lower than the thymoma, with more unilaterality and calcification or bone toothing in the shadow. Proliferative shadows can be identified, while thymoma is rarely seen in the above imaging findings, and it is easier to identify with myasthenia gravis.

2. Thoracic goiter: mostly located in the anterior superior mediastinum, the source of which is mostly the neck goiter through the sternal posterior space into the anterior superior mediastinum, or the residual tissue or ectopic thyroid gland gradually develops, the patient generally does not Symptoms, most of them are found when they are over 50 years old, and women are about 4 times as many as men. Tumors surrounding the tumor may have corresponding symptoms. The diagnosis method is X-ray and CT examination of the neck and chest. All suspects should be routinely done. Radionuclide scanning, tumors can be seen on the left or right side of the trachea in most cases on X-ray films, 80% to more than 90% have tracheal translocation, different from tracheal displacement caused by other lesions, more tracheal displacement caused by intrathoracic thyroid In the cervical trachea, one of its characteristics, the shadow of the mass is mostly round and elliptical, and the edge is clear and sharp. Under the fluoroscopy, the mass moves up and down with swallowing movement. The radionuclide scan can determine the location, size and presence of the tumor. Corresponding lesions, according to the absorption of 131I can also determine the function of the thyroid, if there is no 131I absorption in the normal thyroid position and 131I absorption in the posterior sternal mass can be diagnosed as chest Posterior thyroid gland.

3. Mediastinal malignant lymphoma: It is the most common disease that is not suitable for surgical treatment. Mediastinal tumor is only a local manifestation of this highly malignant systemic disease. In the early stage, there are severe pressure symptoms of the trachea and superior vena cava. The symptoms are rapidly aggravated, and facial, neck, upper limb swelling, superficial lymphadenopathy and hepatosplenomegaly are common phenomena. X-ray shows a large nodular mass that grows rapidly around the trachea and bronchi, typical of one or both mediastinums. In some cases, there may be pleural effusions. Small doses of radiation therapy and chemotherapy can quickly improve the symptoms, and the tumor shadows seen on X-rays are significantly reduced.

4. Mediastinal cysts: mainly anterior mediastinal cysts, more common thymic cysts and cystic lymphangioma, most patients are asymptomatic, the symptoms are mainly caused by increased effusion in the cyst, increased mass, the main basis for diagnosis Radiological examination, showing a thin, low-density space, a smooth and clear edge, semi-circular or circular, CT can determine the relationship between the lesion and the surrounding tissue and can show that the density of the capsule is close to water. However, sometimes it is confused with cystic teratoma. It is often impossible to confirm the diagnosis before surgery. The treatment is mainly to remove the cyst by surgery. It is easier to treat the cyst without obvious adhesion to the surrounding tissue.

5. Thoracic aortic aneurysm: Patients with aneurysms have typical symptoms and signs such as chest tremors and murmurs, tracheal traction, recurrent laryngeal nerve palsy and fluoroscopy with pulsatile masses, etc., which are less common because of The formation of mechanized thrombus in the tumor sac has neither murmur nor pulsation. The shadow of the common X-ray aneurysm cannot be separated from the aorta or the large brachiocephalic blood vessel. This finding has important diagnostic significance. The large blood vessels form an obtuse angle, and in the case of suspicious circumstances, a clear diagnosis of cardiac angiography should be performed.

6. Metastasis: In addition, metastatic lesions from the lungs, breast and cervix or other organs are not uncommon. Occasionally there may be isolated primary lesions of unknown origin, and even the source of metastatic lesions after surgical exploration and autopsy cannot. The diagnosis is diagnosed, so the diagnosis should be comprehensively considered.

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