Tracheal and mediastinal displacement

Introduction CT slices of patients with mediastinal nerve sheath tumors can show that the tumor fills the entire thoracic cavity, the mediastinum shifts to the healthy side, the trachea shifts, is compressed or narrowed. Neurogenic tumors are the most common mediastinal tumors in adults and children. The tumors are classified into benign tumors such as schwannomas, melanoma, Schwannoma, granulosa cell tumors and neurofibroma. Malignant tumors have malignant Schwannoma and neurogenic sources. Sarcoma. Schwann cells from the nerve sheath grow slowly.

Cause

(1) Causes of the disease

Schwannomas

Schwann cells from the nerve sheath grow slowly. On the naked eye, the schwannomas envelope is tightly bound to the originating nerve fibers and is relatively hard, grayish yellow or pink. The cut surface is like an annual ring. Two kinds of cells can be seen under the microscope: Antoni A is a spindle-shaped cell, which is dense and avascular-free grid-like arrangement. Antoni B has a change of myxoma and multiple cystic areas, and the vessel wall is thickened and hyaline. Electron microscopy of Antoni A cells has many small cytoplasmic processes that are emitted from the cell body. Antoni B cells lack these cytoplasmic processes but are rich in cytoplasm and complex organelles. Schwann cell tumors containing melanin occur in the spinal canal in addition to the paraspinal sulcus. Granuloma is the origin of sphincter cells, and Aisner et al. (1988) reported a case of granulomas that occurred simultaneously in the paraspinal sulcus.

2. Neurofibroma

Neurofibromas are less than schwannomas and are composed of nerve cells and nerve sheaths. On the naked eye, there appears to be a capsule, the cut surface is gray and translucent, with small rounded or fusiform swelling, but the true connective tissue boundary is not visible under the microscope. Histologically, the proliferating cell membrane sheath and many axons form a staggered network, and the cells are not arranged in a grid. Under electron microscopy, the tumor is composed of elongated cells that protrude from a few large cytoplasmic processes, and occasionally myelinated or unmyelinated axons are seen in the broad collagen matrix. The plexiform neurofibroma is a diffuse fusiform enlargement of the nerve and/or multiple masses distributed along the nerve. The sympathetic trunk, vagus nerve, and phrenic nerve of the paraspinal sulcus are visible, but the left vagus nerve is near. The lateral ends, ie above the aortic arch or the level of the aortic arch are more common.

3. Neurogenic sarcoma (malignant Schwann cell tumor)

Less than 10% of adult neurogenic tumors are neurogenic sarcomas, and the tumors are mostly located in the posterior mediastinum, and can be seen in the anterior mediastinum; nearby structures are often violated and distant metastasis can occur. Under the microscope, the number of cells was abnormally increased, nuclear polymorphism and mitosis.

(two) pathogenesis

The schwannomas are derived from nerve sheath cells, which occur in the posterior and intercostal nerves of the spinal nerves, and also in the sympathetic and vagus nerves, and the recurrent laryngeal nerve. The incidence of men and women is similar, mostly in people aged 20 to 50 years, there is no difference in the incidence of left and right chest. It occurs more above the chest than below. The size of the tumor varies, usually ranging from 3 to 15 cm in diameter (median value 5.0 cm).

Benign sphincter-derived tumors can be divided into two categories: schwannomas (benign Schwannoma) and neurofibromas, and rare melanoma Schwannoma and granulosa cell tumors. Malignant people are malignant schwannomas or neurogenic sarcomas. The schwannomas are mostly located on one side of the nerve trunk, wrapped in the nerve outer garment or clothing, so that the nerve trunk is eccentric fusiform expansion, but the nerve does not penetrate into the tumor, so the operation is easy to remove and does not damage the nerve. Neurofibromas occur mostly in the 20 to 40 years old, and are mostly part of the neurofibromatosis Von Reckling-hausens disease. The main cellular component is also the nerve sheath cells, which are tumor-like masses formed by peripheral nerve fiber components or diffuse hyperplasia. The intrathoracic mediastinal neurofibromatosis is often single, and the malignant rate of neurofibromatosis in such patients can be as high as 4% to 10%. The nerve sheath-derived tumor of the spinal nerve root and the intercostal nerve can expand and expand in the intervertebral foramen and has a dumbbell shape. The tumor outside the intervertebral foramen is often larger than the inner part of the intervertebral foramen. Occasionally, two uncommon sphincter-derived tumors are seen in the mediastinum: melanoma schwannomas and granulocyte tumors. The latter was confirmed to originate from neuromembrane cells and is a malignant lesion classified as malignant schwannomas. Neurogenic sarcoma (malignant Schwann cell tumor) accounts for less than 10% of adult neurogenic tumors, and is more common in young people aged 10 to 20 or older people aged 60 to 70 years. Structures near the tumor are often violated and distant metastases can occur. Under the microscope, the number of cells was abnormally increased, nuclear polymorphism and mitosis.

an examination

Related inspection

Chest CT examination chest B-ultrasound

Chest X-ray

The neurogenic tumors seen were basically similar, and there were no significant differences between benign and malignant manifestations. The orthotopic X-ray film shows a circular or elliptical uniform density of shadows in the thoracic cavity, occasionally triangular or lobulated, with the inner edge often located in the mediastinum. The lateral radiograph shows that the tumor is located in the paraspinal area of the spine with clear boundaries. Adjacent bones may also change.

For example, the ribs and vertebral bodies are eroded, the intervertebral foramen is enlarged, the intercostal space is widened, and the ribs are everted, but often the nature of the tumor cannot be explained. This is because the tumor growth causes local compression. The pedicle is flattened, and even the pedicle transverse vertebral body is destroyed, accompanied by an enlarged intervertebral foramen, which is a special X-ray sign of the posterior mediastinal dumbbell-like tumor. The upper digestive tract tincture tablets also showed a distortion of the esophagus.

2.CT scan display

The tumor is located in the posterior mediastinum, much closer to the paravertebral, and the tumor boundary is clear. It is round, oval, and some cases of benign or malignant tumors may have lobes.

In patients with multiple neurofibromatosis, the detection rate of CT scan is often higher than that of ordinary chest X-ray.

3. Magnetic resonance imaging (MRI)

Enhanced images of T1 and T2 may show that neurofibroma has a high-density characteristic peripheral zone and a medium-density central zone, while schwannomas are heterogeneous, high-density zones. CT or MRI can determine the extent to which the tumor invades the spinal canal, which can also be used to determine the extent of involvement. However, enhanced spinal X-ray examination is currently used to understand tumor invasion. Such as a giant neurogenic tumor in one side of the chest, X-ray films, CT films can show that huge tumors occupy the entire thoracic cavity, mediastinum shift to the healthy side, tracheal displacement, compression or narrowing, the affected side of the lung is compressed , common side of the chest fluid.

Differential diagnosis

Let the patient head in the middle position, use the right middle finger to touch the trachea along the sternal notch. The index finger and the ring finger are on the left and right sides of the sterno-lock joint respectively. See if the middle finger is equidistant from the other two fingers, or touch the trachea with the middle finger. The size of the gap between the middle finger and the thoracic mammary muscles on both sides to determine whether the trachea is displaced. Tracheal displacement is important for the diagnosis of chest diseases.

When one side of the pleural effusion, gas accumulation or space-occupying new organisms, the trachea is pushed to the healthy side due to increased intrathoracic pressure; when one side of the atelectasis, pleural thickening and adhesion, the trachea is pulled Pull to the affected side.

Mediastinal widening: mediastinal inflammation, hematoma, abscess, paratracheal lymph node, mediastinal tumor and cyst, superior vena cava and azygotic vein dilatation, aneurysm, mediastinal pleural effusion, etc. can widen the mediastinum, combined with clinical and Medical history, if necessary, tomography, angiography and other inspection methods to determine the reasons for the widening.

The tracheal mediastinum and the shift of the heart to the healthy side are clinically diagnosed symptoms of tuberculous pleurisy. Tuberculous pleurisy is an exudative inflammation caused by tuberculosis directly invading the pleura from the primary lesion of the proximal pleura, or spreading to the pleura via lymphatic blood.

1. Chest X-ray: The neurogenic tumors seen are basically similar, and there are often no significant differences between benign and malignant manifestations. The orthotopic X-ray film shows a circular or elliptical uniform density of shadows in the thoracic cavity, occasionally triangular or lobulated, with the inner edge often located in the mediastinum. The lateral radiograph shows that the tumor is located in the paraspinal area of the spine with clear boundaries. Adjacent bones may also change.

For example, the ribs and vertebral bodies are eroded, the intervertebral foramen is enlarged, the intercostal space is widened, and the ribs are everted, but often the nature of the tumor cannot be explained. This is because the tumor growth causes local compression. The pedicle is flattened, and even the pedicle transverse vertebral body is destroyed, accompanied by an enlarged intervertebral foramen, which is a special X-ray sign of the posterior mediastinal dumbbell-like tumor. The upper digestive tract tincture tablets also showed a distortion of the esophagus.

2. CT scan showed that the tumor was located in the posterior mediastinum, much closer to the paravertebral, and the tumor boundary was clear. It is round, oval, and some cases of benign or malignant tumors may have lobes.

In patients with multiple neurofibromatosis, the detection rate of CT scan is often higher than that of ordinary chest X-ray.

3. Magnetic Resonance Imaging (MRI): Enhanced images of T1 and T2 can show that neurofibromatosis has a high-density characteristic peripheral zone and a medium-density central zone, while schwannomas are heterogeneous high-density zones. CT or MRI can determine the extent to which the tumor invades the spinal canal, which can also be used to determine the extent of involvement. However, enhanced spinal X-ray examination is currently used to understand tumor invasion. Such as a giant neurogenic tumor in one side of the chest, X-ray films, CT films can show that huge tumors occupy the entire thoracic cavity, mediastinum shift to the healthy side, tracheal displacement, compression or narrowing, the affected side of the lung is compressed , common side of the chest fluid.

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