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Mediastinal lesions

Introduction
Cause
Examine
Diagnosis

Introduction

Introduction Mediastinal diseases include mediastinal tumors (benign and malignant), cysts, acute and chronic mediastinal inflammation, mediastinal spasm, mediastinal emphysema, etc. The chest cavity of the human body is divided into two pleural cavities, and the middle part of the pleural cavity on both sides is called the mediastinum. The mediastinum contains the heart, large blood vessels in the chest, trachea, esophagus, nerves and lymphoid tissues. The mediastinum can be divided into several regions, from the sternal angle (ie, the intersection of the sternum stem and the sternum body, which can be touched on the body surface to show a distinct transverse sac), and the horizontal line is drawn backward to the lower edge of the fourth thoracic vertebral body. Above the line is called the upper mediastinum, and the line is called the lower mediastinum. The upper mediastinum is bounded by the trachea, the front is the anterior superior mediastinum, and the posterior is the posterior superior mediastinum. The lower mediastinum is divided into three parts: the front, the middle and the back. The front of the pericardium is the anterior mediastinum. The pericardium is called the mediastinum. The posterior mediastinum is called between the pericardium and the spine. The anterior superior mediastinum mainly has thymus and intrathoracic thyroid gland. The posterior superior mediastinum has trachea, esophagus, aortic arch and its three head-arm vascular branches, thoracic duct, vagus, nerve and so on. The lower anterior mediastinum has a lower thymus, lymph nodes, fat and connective tissue. The posterior mediastinum has esophagus, thoracic duct, descending aorta and its branches, azygous veins, semi-odd veins, vagus and sympathetic nerves.

Cause

Cause

Intrathoracic goiter (or tumor):

Intrathoracic goiter is mostly due to the lower pole of the thyroid gland, adenoma or nodule of the isthmus. The effect of gravity, flexion and extension of the neck, swallowing activity, and negative pressure in the thoracic cavity gradually follow the anterior fascia of the vertebral body and before the trachea. After the fascia, descend into the mediastinum. Because the aorta is on the left side of the upper mediastinum, the descending thyroid is mostly on the right side, before the anterior carotid sheath, the innominate vein and the superior vena cava, a few are located before and after the esophagus; sometimes it can also be located in the upper left mediastinum, pushing the trachea to the right. Side; the other is a relatively rare embryonic developmental abnormality, that is, ectopic thyroid. In the embryonic stage, the thyroid gland and parathyroid gland are from the 3rd and 4th sacral arches (in the medial side of the zygomatic arch and the cleft palate) adjacent to the pericardial vascular. If the dysplasia is abnormal, the ectopic vagus thyroid can be shared with the pericardium and large blood vessels. The part descends into the chest and is located in the upper and lower mediastinum. If there is a fibrous band in the upper mediastinum connected to the thyroid gland. Sometimes it can be located behind or below the sternum, behind the trachea, esophagus, etc.

Thymic tumor:

The thymus is the primary lymphoid organ of the immune system, which produces immune lymphocytes that regulate the immune response of lymphocytes and bone marrow-regulated lymphocytes. And related to autoimmunity. Such as thymoma manifestations of systemic myasthenia gravis, which is related to abnormal immune response. Pregnancy, breastfeeding, exposure to radiation, and application of adrenocortical hormone can affect thymus function.

Teratogenic tumors:

The cause of this disease, at present, more agree with GR Minot's view that it has the same source as the thymus, thyroid, and parathyroid glands. It can be explained that the tumor is composed of multiple germ layer tissues. In the past, these tumors were divided into three types: epithelial cysts, dermoid cysts, and teratomas. Epithelial cysts are derived from ectodermal tissue; dermoid cysts contain outer and mesoderm tissues; teratomas contain outer, middle, and endoderm tissues. These three types of tumors cannot be clearly distinguished in histology, hence the name teratoma. The site of occurrence is mostly in the anterior superior mediastinum, protruding to one side, and the volume is from the size of the pigeon egg to the chest of the full side. It is rarely found in the neck, the upper edge of the sternum, and the posterior mediastinum, and very few are found in the bronchi.

Mediastinal neurogenic tumor:

This tumor is from Schwann cells, ectoderm, and is often called Schwannoma. The mediastinal neurogenic tumor is most common with neurofibromatosis, ganglioneuroma, and Schwannoma. Others include malignant Schwannoma, sympathetic fibroma, sympathetic ganglion cell tumor, neurofibrosarcoma, neuroblastoma, parasympathetic ganglionoma, chemoreceptor tumor, pheochromocytoma and the like. Mediastinal malignant neurogenic tumors are rare, the ratio of benign to malignant is 10:1, the tumor site is mostly in the posterior mediastinum, and the upper mediastinum is more common than the lower mediastinum. Posterior mediastinal neurofibromatosis and Schwannoma are derived from the spinal nerves, intercostal nerves, and located in the paravertebral sulcus.

Mediastinal lymphoid tumors and other sarcomas:

Lymphoma is located in the mediastinum. Divided into Hodgkin's disease and non-Hodgkin's lymphoma, the latter including lymphosarcoma and reticuloma. Other mediastinal sarcomas have fibers, fats, and leiomyomas. Hodgkin's disease is an independent type of lymphoma. It is characterized by the discovery of Reed-Sternberg II cells (referred to as RS cells) in tumor tissues. The cells have highly lobulated nucleus and multi-chromosomal giant mesenchymal cells with large nucleoli. Cellular tissue morphology unique to Chikin's disease. In pathology, lymphosarcoma is divided into two types, lymphoblastic type and lymphocytic lymphosarcoma. Reticulocyte sarcoma is divided into mature and immature types. The mediastinal sarcoma composed of other tissues includes fibers, fat, and leiomyosarcoma. The mediastinal lymphatic system has a high degree of malignancy, rapid growth, and easy metastasis. Fibrosarcoma grows slowly, and poor cell differentiation can be malignant and metastasized. Leiomyosarcoma and liposarcoma are less malignant.

Mediastinal hemangioma and lymphangioma: both are rare, hemangioma mostly located in the anterior and posterior superior mediastinum, lymphangioma mostly located in the anterior mediastinum and posterior superior mediastinum, the growth position of the left and right chest is similar.

Congenital mediastinal cysts include pericardial cysts, tracheal cysts, and esophageal cysts. The pericardial cyst is formed by the tissue left by the bud of the pericardial cavity. It is attached to the outer wall of the pericardium. The wall of the cyst is thin and transparent. The inner wall is mesothelium, and the capsule contains clear liquid. The bronchial cyst is derived from the part of the foregut in the embryonic stage and forms into the chest cavity as the bronchus and lung develop. The wall of the capsule is provided with a pseudostratified ciliated epithelium with scattered smooth muscle and cartilage. The capsule contains yellow blood mucus. Often located near the tracheal carina, can be prominent in the anterior or posterior or superior mediastinum, more changes in the site, very few malignant changes. The esophageal cyst is caused by the fusion of the upper digestive tract vacuoles in the embryonic stage. The mucosa of the cyst is mostly a typical gastric mucosa, and some have the function of secreting acid. The outer wall is similar to the esophageal wall and consists of two layers of smooth muscles. The muscular layer of the cyst and the esophageal muscle layer are integrated into one body, and there is no obvious boundary. There is no serosa outside the muscular layer, and there is no sacral connection between the esophagus and the esophagus.

Acute mediastinal inflammation:

The cause of chronic mediastinal inflammation is unknown. According to reports in the literature, tuberculosis, upper respiratory tract infection, influenza, pneumonia, suppurative infection, tissue patina, actinomycosis, radiation therapy, syphilis, etc. can cause this disease, mostly caused by non-specific inflammation. Chronic mediastinal inflammation is one of the important causes of superior vena cava obstruction, and it is also the late manifestation of the disease.

Mediastinum:

The reason is that the pressure in one side of the chest cavity is greater than the contralateral side, and the side with a large pressure presses the mediastinum into the weak side. Such as one side of the lungs, high pressure pneumothorax, a large number of pleural effusion, giant lung cysts and lung tumors and other pushes. Or the side of the sputum caused by severe chest fibrosis due to thoracic lesions, atelectasis or pneumonectomy on the side, can pull the healthy side, resulting in mediastinal hernia. The mediastinum is different from the mediastinal shift. But the two often exist at the same time. The mediastinal shift is due to the pressure on the disease side or the extensive fiber contraction or pulling on the disease side, causing the entire mediastinal organ to shift to the other side.

Mediastinal emphysema:

The mediastinal pleural connective tissue is filled with gas for mediastinal emphysema, which is a sign rather than a separate disease. Due to the rupture of the alveoli, the gas gradually invades the mediastinum from the perivascular space of the pulmonary interstitial; it can also be caused by the rupture of the pleural and mediastinal pleura of the lung, the pneumothorax, trachea, bronchus or esophagus perforation caused by gas entering the pleura. The gap enters the mediastinum. The mediastinal gas can continue to rise along the anterior fascial space of the spine, the trachea, and the perivascular space to the neck, forming subcutaneous emphysema in the neck; or pneumothorax caused by gas rupture through the mediastinal pleura into the pleural cavity. In addition, gastrointestinal rupture, gas up through the mesentery, posterior peritoneal space up to the mediastinum; can also be caused by subcutaneous emphysema in the neck to the mediastinum; use of artificial respirator pressure, artificial gastro-abdominal surgery after peritoneal injection Forms mediastinal emphysema.

In trauma, such as esophagus, tracheal stab wounds, chest closure injury, trachea, bronchial tubes, esophageal rupture, gas into the mediastinum; iatrogenic trauma, such as endoscopy, tracheotomy, can also allow gas to spread into the subcutaneous diffusion To the mediastinum, causing mediastinal emphysema. The severity of the symptoms of mediastinal emphysema may vary depending on the amount of gas and whether there is a secondary infection. Simple mediastinal emphysema may have shortness of breath, chest tightness, and poor breathing. Due to trauma associated with high-pressure pneumothorax, internal bleeding may have difficulty breathing, and even life-threatening.

Examine

an examination

Related inspection

Chest radiography mediastinoscopy lung ventilation function chest MRI chest CT examination

Intrathoracic goiter (or tumor):

It is a common mediastinal tumor. Most of the pathological examinations have a complete fibrous envelope, which is nodular and lobulated, with a soft texture or medium hardness. The profile is white or raw, and may also have cystic changes, hemorrhage or necrosis. The size of the tumor varies from 2 to 30 cm or more. Histocytic morphology is divided into three types: epithelial cells (mainly glandular epithelium), lymphocytes (mainly lymphocytes), and mixed (both types of cells). In addition, there are spindle cells, which are also epithelial, and thymoma is classified into malignant and benign. Malignant people only account for 20 to 43% of thymoma. Benign people have intact capsules and non-invasive growth. Malignant tumors lack intact capsules and invade surrounding tissues. If pleural invades, pleural effusion can occur. If there is vascular erosion in the tumor tissue, or cell nuclear histology can be seen in the deep nuclear staining and a large number of dividing cells, it may be a malignant lesion. However, most of the malignant changes are not accompanied by the characteristics of this histology, so it is necessary to confirm the diagnosis according to the clinical operation and the development of the disease.

Teratogenic tumors:

Cyst-like teratoma showed a smooth round shape from the pathological tissue. The substantial person is lobulated, and it is difficult to separate from the surrounding tissues and organs when there is a secondary infection. The inner wall of the cystic person is a pseudo-stratified ciliated epithelium, columnar or squamous epithelium, and the outer wall is fibrous tissue, which thickens when infected. The contents of the capsule are viscous turbid yellow or bloody liquid, and contain hair, teeth, sebaceous glands, cholesterol crystals, muscles, cartilage, bones, blood vessels, etc., or contain pancreas, thymus, thyroid, bronchial epithelium, intestinal epithelium, and liver. Embryo tissue. Increased teratogenic tumors can compress nearby organs, rupture to adjacent tissues during infection, can break into the lungs, bronchus, pericardium, neck and chest subcutaneous and thoracic cavity, a small amount into the superior vena cava, pulmonary artery and aorta, can lead to Major bleeding.

Mediastinal neurogenic tumor:

Benign neurogenic tumors have a capsule with a smooth surface (the nerve fiber capsule is sometimes incomplete), medium hardness, nodular, dumbbell-shaped, half in the chest, half in the intervertebral foramen, and the base of the tumor can also be pedicled Shaped or branched. Its profile is light yellow or yellowish white, and it can have multiple small cysts containing mucus. Often accompanied by bleeding, necrosis and glassy changes. However, the above three common neurogenic tumors are difficult to distinguish in clinical, X-ray examination and even visual observation. Microscopic observation of neurofibroma can be seen in various parts of nerve fibers, and sheath cells, nerve axons and a large number of fibrous tissues surrounding nerve fibers. Schwann's tumor can be seen under the microscope: two kinds of tumor cells: one with large nuclei, few cytoplasm, and protrusions. A small nucleus with many cytoplasm. A large number of sympathetic ganglion cells are seen in the neuroblastoma and have axons and basement membranes.

Mediastinal lymphoid tumors and other sarcomas:

Lymphoma is located in the mediastinum. Divided into Hodgkin's disease and non-Hodgkin's lymphoma, the latter including lymphosarcoma and reticuloma. Other mediastinal sarcomas have fibers, fats, and leiomyomas. Mediastinal hemangioma and lymphangioma, both rare, hemangioma mostly located in the anterior and posterior superior mediastinum, lymphangioma mostly located in the anterior mediastinum and posterior superior mediastinum, the growth position of the left and right chest is similar.

Clinical manifestations:

1 compression symptoms, tumor volume can be asymptomatic. Large volume can oppress nearby organs and the corresponding symptoms occur. If the superior vena cava obstruction syndrome occurs in the upper vena cava, the venous pressure on the side of the superior vena cava is increased, sometimes up to 20 ~ 50cmH2O. When the patient is standing upright, the jugular vein is filled and relieved after the activity. When the venous stasis is severe, there may be lip purpura, large liver, and subcutaneous vein filling of the upper chest wall to form a collateral circulation. Compression of the lungs and bronchus can cause difficulty in breathing and atelectasis. Pressing the recurrent laryngeal nerve can make the recurrent laryngeal nerve numb and hoarse; pressing the phrenic nerve can paralyze the diaphragm.

2 local symptoms, such as chest pain, poor breathing, wheezing, shortness of breath, chest tightness, cough, fever, sputum, hemoptysis, etc. If a large tumor and sac breaks into the pericardium, an acute pericardial tamponade can be produced. Patients with teratogenic tumors may have hair, teeth, sebaceous glands and the like. Hemangiomas invade the spinal cord and can compress the spinal cord to produce paraplegia.

3 systemic manifestations other than the chest, such as thymoma can be combined with various immune response abnormalities and diseases, myasthenia gravis.

diagnosis:

X-ray positive and lateral chest radiographs, especially thoracic and oblique X-ray fluoroscopy and photography, contribute to the localization and differential diagnosis of mediastinal tumors. The mediastinal tomography can further determine the relationship between the location and nature of the lesion in the mediastinum and the organs in the mediastinum.

Computer tomography (CT):

For the diagnosis and differential diagnosis of mediastinal tumors, not only can early microscopic tumor foci not found by conventional X-rays, but also the correlation between tumors and surrounding organs can be found in detail, and the method of surgical treatment can be determined. In addition, according to the size of the CT value, qualitative and differential diagnosis of tumors such as benign, malignant, cystic, solid and adipose tissue can be made more accurately. Congenital mediastinal cysts include pericardial cysts, tracheal cysts, and esophageal cysts.

Clinical manifestations:

Pericardial cysts rarely compress the heart, with fewer symptoms and slower growth. Tracheal cysts have few symptoms in adults. Children may experience difficulty breathing, compress the esophagus, and break into the bronchi to cause secondary infection. The symptoms of esophageal cysts are more common in infants, and different levels of dyspnea and cough can occur. If the ulcer occurs on the wall of the capsule, it can cause bleeding and death.

Diagnostic chest X-ray fluoroscopy is a simple diagnostic method. It can rotate the body position to check the shape of the cyst from different directions, and whether there is vascular pulsation (identification with hemangioma). Pericardial cysts are mostly circular or elliptical shadows with anterior palpebral horns. The density is light and uniform, the edges are sharp, and they are inseparable from the pericardium. The bronchial cysts are round or elliptical, with sharp edges, uniform image density, and trachea. The same, there can be liquid level. The esophageal cyst showed partial esophageal dilatation, and the shadow and the esophagus could not be separated. The three were mainly surgical treatment.

Diagnosis of mediastinal inflammation, mediastinal hernia and mediastinal emphysema:

The translucent area extending beyond the trachea to the contralateral side is the lung tissue that is invaded to the opposite side, and the lung texture is sparse. Bronchial angiography can lack tracheal imaging; mediastinal emphysema can be seen on the posterior anterior X-ray chest radiograph. The white strip of mediastinal pleura is pushed to the sides by the black inflatable mediastinal connective tissue image. Especially at the outer edge of the left pericardium, the airway is also visible along the outer edge of the descending aorta, and the gas is visible along the deep fascial space of the neck to reach the black translucent area of the neck. The lateral chest radiograph shows a translucent air shadow that deepens the posterior sternal space. When the pericardial gas accumulates, the gas accumulates mainly at the root of the heart, and the ridge of the pericardium is seen. The mediastinal emphysema is more obvious on both sides of the upper mediastinum.

Diagnosis

Differential diagnosis

Acute mediastinal inflammation:

Acute mediastinal connective tissue purulent inflammation caused by various causes of infection. Such as chest traumatic trauma, esophageal or tracheal rupture, perforation. Esophagus, bronchoscopy, and perforation of esophageal cancer. Infection after surgery, anastomotic leakage after esophagectomy, retroperitoneal infection extended to the mediastinum, oral and neck infection spread downward, can cause mediastinal inflammation. Its clinical manifestations are acute onset, high fever, chills, headache, and shortness of breath. Abdominal pain and jaundice can occur when the infection is down. When invading the chest, acute empyema can occur, and the upper empyema of the upper lung can also be formed. In severe cases, septic shock can occur.

Mediastinum:

A portion of the mediastinal pleura enters the contralateral pleural cavity through the mediastinum, called the mediastinum. This is a symptom, not a separate disease. The reason for this is because there are two anatomical weak areas in the posterior mediastinum: one is above the aortic arch and the azygous vein, which is equivalent to the third to fifth thoracic level, the anterior boundary is the esophagus, trachea and large blood vessels, and the posterior border is the spine; The aorta and azygium are equivalent to the fifth thoracic vertebra, the anterior boundary is the heart and the large blood vessels, and the posterior border is the descending aorta and the spine. Previously, the upper mediastinum was more common.

The reason for the occurrence of mediastinal fistula is that the pressure in one side of the chest is greater than the contralateral side, and the side with greater pressure compresses the side of the mediastinum into the weak side. Such as one side of the lungs, high pressure pneumothorax, a large number of pleural effusion, giant lung cysts and lung tumors and other pushes. Or the side of the sputum caused by severe chest fibrosis due to thoracic lesions, atelectasis or pneumonectomy on the side, can pull the healthy side, resulting in mediastinal hernia. The mediastinum is different from the mediastinal shift. But the two often exist at the same time. The mediastinal shift is due to the pressure on the disease side or the extensive fiber contraction or pulling on the disease side, causing the entire mediastinal organ to shift to the other side. The mediastinal fistula is mainly caused by the primary lesions of the contralateral chest (such as pulmonary bullae, high-pressure pneumothorax) and the pressure of the septum itself. There may be difficulty breathing, coughing, shortness of breath, and wheezing. In severe cases, it can affect the blood output of the heart and cause respiratory and circulatory failure.

Mediastinal emphysema:

Diagnosis and treatment of mediastinal inflammation, mediastinal hernia and mediastinal emphysema:

X-ray inspection is an important method. Mediastinal inflammation manifests as mediastinal widening; mediastinal fistula from different body positions (posterior, lateral position) X-ray observation, or projection of the tomogram, can show the position of the sputum and trachea, esophagus, and determine whether it is mediastinal shift. The translucent area extending beyond the trachea to the contralateral side is the lung tissue that is invaded to the opposite side, and the lung texture is sparse. Bronchial angiography can lack tracheal imaging; mediastinal emphysema can be seen on the posterior anterior X-ray chest radiograph. The white strip of mediastinal pleura is pushed to the sides by the black inflatable mediastinal connective tissue image. Especially at the outer edge of the left pericardium, the airway is also visible along the outer edge of the descending aorta, and the gas is visible along the deep fascial space of the neck to reach the black translucent area of the neck.

The lateral chest radiograph shows a translucent air shadow that deepens the posterior sternal space. When the pericardial gas accumulates, the gas accumulates mainly at the root of the heart, and the ridge of the pericardium is seen. The mediastinal emphysema is more obvious on both sides of the upper mediastinum. The primary treatment for acute mediastinal inflammation is the treatment of the cause, infection control and supportive therapy (transfusion, infusion, oxygen supply). Surgical procedures for collateral circulation and vascular bypass surgery are required for chronic mediastinal inflammation with severe superior vena cava obstruction. The treatment of mediastinal fistula is mainly to treat the primary disease and remove the cause, so that the mediastinum can be quickly recovered. If there is only a small amount of gas in the mediastinal emphysema, it can be cured. The severe one is also the cause of treatment (such as trauma, emphysema, rupture of lung vesicles, etc.). If the gas absorption is slow and the patient has difficulty breathing or affects the pronunciation, the sternal incision can be used as the incision to the subcutaneous tissue.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.

Mediastinal lesions

Introduction

Cause

Examine

Diagnosis

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