Overview
Thymus is an important immune organ in human body. Thymic tumors originating from thymic epithelial cells or lymphocytes are the most common, and thymoma is the third among mediastinal tumors after teratoma and neurogenic tumors, and patients with thymoma may or may not have symptoms of myasthenia gravis.
Diagnosis
X-ray examination is an important method to detect and diagnose thymoma, but some thymomas are in the shape of flat pieces lying on top of large blood vessels in the heart, and this type is the most difficult to diagnose in X-ray examination. Chest CT is an advanced and sensitive method to examine mediastinal tumor, which can accurately show the location, size, protrusion to one side or both sides, the edge of the tumor, the presence of surrounding infiltration and the determination of surgical resectability, and has its special value for cases that cannot be diagnosed by clinical and general X-ray examination.
Pathological changes]
Pathologically thymoma is named after the cellular component that accounts for more than 80%. It is divided into epithelial cell type and mixed epithelial cell lymphocyte type. It is difficult to distinguish benign or malignant thymoma purely from pathological morphology, and it is more appropriate to classify invasive and non-invasive thymoma according to clinical manifestations, visual observation during surgery and pathological morphological characteristics. However, it is customary to refer to benign and malignant thymomas.
The differentiation between benign and malignant thymoma A is based on the clinical presentation and the findings during surgery. During surgery, attention should be paid to
①Whether the tumor has an intact envelope or not;
②Whether the tumor has aggressive growth;
③Whether there is distant metastasis and intra-thoracic implantation;
④The anomalies of cell morphology under microscope, and comprehensive analysis can reach the correct conclusion. If the tumor has an intact fiber envelope at the time of surgery, the tumor grows within the envelope and does not infiltrate with the surrounding organs, and is easily removed by surgery, it is considered benign or non-invasive thymoma. When the tumor invades out of the envelope and invades the surrounding organs or tissues (pericardium, pleura, lung and blood vessels, etc.), and cannot be removed or completely removed by surgical operation, or if intra-thoracic implantation or pleural metastasis is found at the time of operation, it is considered malignant or invasive thymoma.
Clinical manifestations]
Like any mediastinal tumor, the clinical symptoms of thymoma arise from the compression of surrounding organs and the symptoms specific to the tumor itself – combined syndrome. Small thymoma has no clinical complaints and is not easily detected. When the tumor grows to a certain size, the common symptoms are chest pain, chest tightness, cough and anterior chest discomfort. The nature of chest pain is not characteristic, the degree varies and the location is not specific, generally speaking, it is mild and often treated symptomatically without further examination. If the symptoms persist for a long time, some patients may undergo X-ray examination, or some patients may find mediastinal mass shadows during chest X-ray or chest radiography.
The overlooked thymoma often grows to a large size at this time, compressing the veins or showing signs of superior vena cava obstruction syndrome. Severe chest pain, rapid worsening of symptoms within a short period of time, severe irritating cough, dyspnea due to pleural effusion, shortness of breath due to pericardial effusion, and skeletal pain of peripheral concern all suggest the possibility of malignant thymoma or thymic carcinoma.
The unique manifestation of thymoma is the combination of certain syndromes, such as myasthenia gravis (MG), pure red blood cell aplastic anemia (PRCA), hypoglobulinemia, nephritis nephritis syndrome, rheumatoid arthritis, dermatomyositis, lupus erythematosus, and megalophagia.
Complications
1, myasthenia gravis (MG) has long been found to be related to the thymus gland (or thymoma). Myasthenia gravis can be clinically divided into 3 types, such as eyelid drooping, long-lasting fatigue, double vision, for the eye muscle type; upper limb extension can not last, walking a little far need to sit down to rest, for the trunk type; chewing and swallowing effort, and even respiratory muscle paralysis, for the medulla oblongata type. The most dangerous clinical condition is myasthenia gravis, in which the patient must be assisted by artificial respiration because of respiratory muscle paralysis. It is believed that myasthenia gravis is an autoimmune disease, mainly due to the mutation of the thymus gland by certain stimuli, which cannot control certain forbidden cell lines and allows them to differentiate and proliferate, resulting in an immune response to its own components (transverse muscles) and myasthenia gravis.
Anti-acetylcholinesterase drugs, such as bromipyridamole, have been used for many years in the treatment of myasthenia gravis, and in recent years immunosuppressive drugs, such as hormones and cyclophosphamide, have been added.
The indications for surgical treatment of myasthenia gravis are patients with myasthenia gravis with or without thymoma, taking anti-acetylcholinesterase drugs with increasing doses without symptom reduction, or myasthenia gravis crisis and recurrent respiratory infections.
2. Pure red blood cell aplastic anemia (PRCA)
One of the coexisting diseases with thymoma is pure red blood cell aplastic anemia. Pure red reoccurrence can be primary and the cause is unclear. It can also be secondary to drugs, infections and tumors. Experimental studies suggest that PRCA is an autoimmune disease with unknown causes leading to an autoimmune response to red blood cell antigens that can be present in the human thymus. Thymoma itself does not have a direct effect on red blood cell growth; it may be the case that thymoma enhances the sensitivity of the immune system or that thymoma is induced by a highly sensitive proliferative system.
3. Nephrotic syndrome nephritis The relationship between nephrotic syndrome nephritis and thymoma is unknown. Nephrotic syndrome can be part of the systemic manifestations of certain tumors, such as Hodgkin’s disease. The possible explanation is that thymoma forms a cross-reaction with the antigen-antibody complexes of glomerulonephritis.
【Treatment measures
(1) Treatment principle: Thymoma should be surgically removed once diagnosed. The reason is that the tumor continues to grow and enlarge, compressing the neighboring tissues and organs to produce obvious clinical symptoms; it is difficult to judge the benignity and malignancy of the tumor simply from clinical and X-ray performance; moreover, benign tumors can also become malignant. Therefore, no matter benign or malignant thymoma, it should be removed as soon as possible. If there is a malignant thymoma that can be removed, pathological biopsy can be performed to guide postoperative treatment, and postoperative radiation therapy for partial resection can relieve symptoms and prolong patient survival.
(2) Thoracoscopic surgery: For relatively small thymoma, two 1-cm incisions and one 3-cm incision can be made on the right chest wall to complete the enlarged thymectomy. The use of thoracoscopic treatment not only makes the incision beautiful and reduces trauma, but also has a quick postoperative recovery and can be discharged within 5 days after surgery.
(3) For patients who cannot be treated by thoracoscopic surgery, conventional surgery is feasible: for small thymomas protruding to one side, the anterior external intercostal thoracotomy is mostly used, and for larger tumors protruding to both sides, the anterior median thoracotomy can be used. In recent years, the anterior median thoracic incision has been used more often to remove the thymoma and the contralateral thymus at the same time to prevent the possibility of severe myasthenia gravis in the future. Some people also use transverse sternal transverse thoracotomy to remove the tumor. The thymoma can also be removed through a cervical incision if the tumor is small and close to the neck.