What Is a Paraganglioma?

English name: paraganglioma

Paraganglioma

English name: paraganglioma

Chinese name: Paraganglioma

Explanation of terms: Paraganglioma mainly occurs in the head and neck, of which carotid body tumors, jugular vein spheroid tumors, and vagal paraganglioma account for 98%, and the hair originates in the throat, nasal cavity, orbit, and aorta.

Paraganglion-derived tumors originate from parasympathetic ganglia, referred to as "paraganglia". Paraganglion is relatively speaking to the ganglia in the sympathetic nerve trunk, most of which are located beside the sympathetic nerve trunk. Occasionally, it is also found in distant parts such as the internal organs. According to the response of the primary cells to chromic salts, the paraganglion differs from chromaffinous and non-chromophoric. Therefore , paraganglioma also has chromaffinic and non-chromophoric distinctions. Pheochromochromosomal paraganglioma is mainly represented by adrenal medulla. The tumors that cause it are called "pheochromocytoma"; tumors that are not pheochromoparaganglioma are often referred to as "paraganglioma". It is also called "Nonchromaffin paraganglioma" and "Chemodectoma" in the literature.

Cause

(I) Causes of Onset

Paraganglion-derived tumors originate from parasympathetic ganglia, referred to as "paraganglia". Paraganglion is relatively speaking to the ganglia in the sympathetic nerve trunk, most of which are located beside the sympathetic nerve trunk. Occasionally, it is also found in distant parts such as the internal organs. According to the response of the primary cells to chromium salts, the paraganglioma differs from chromaffinous and non-chromophoric. Therefore, paraganglioma also has chromaffinic and non-chromophoric distinctions. Pheochromochromic paraganglioma is mainly represented by adrenal medulla, and the tumors arising from it are commonly called "pheochromocytoma". Tumors that are not associated with pheochromophytic paraganglioma are often referred to as "paraganglioma". It is also called "Nonchromaffin paraganglioma" and "Chemodectoma" in the literature.

Mediastinal pheochromoparaganglioma is rare, accounting for less than 1% of all mediastinal tumors and less than 2% of all pheochromocytomas. Although the vast majority occur in the anterior mediastinum, they originate from island-like tissues on the aorta or on the paraganglia of the main and pulmonary arteries, the atrium, and the pericardium. Paraganglioma of the heart mostly occurs in the left atrium, left ventricle, and left atrioventricular sulcus, and can also occur in the right atrium and right ventricle. Others originate from aortic sympathy and paraganglia, and are mostly located in the posterior mediastinum along the costal sulcus. Tumors vary in size, ranging in diameter from 1 to 2 cm to 25 cm. Most are benign, only about 10% are malignant. Surgery specimens are usually 5-6 cm. Only about 14% of the patients are clinically affected. The size of the tumor is not necessarily proportional to the severity of the symptoms. Sometimes the smaller patients have obvious symptoms, while the relatively large ones remain "physiologically peaceful", only by accident during autopsy. Tumors are mostly spherical, oval, or slightly lobulated. The capsule is not obvious in the small volume, and the complete capsule is always in the larger one. Most tumors are solid. Fresh specimen cuts are gray-red, and bleeding, necrosis, and cystic lesions are common. In formalin solution (or exposure to air) it gradually turns into tan. When it meets the chromium salt solution, the color will become darker immediately, and the catecholamine oxidation process will be greatly accelerated in the sun.

Pheochromocytoma can be accompanied by other APUD tumors at the same time or successively, such as thyroid malignant C-cell tumor ("meseloid carcinoma"), pituitary adenoma, parathyroid adenoma, islet cell tumor, carcinoid, and neurofibromatosis, etc. , Become one of the components of endocrine adenoma.

Non-pheochromaffic paraganglioma ("paraganglioma", "allergic tumor") is relatively rare. Zhang Xun et al. (1994) reported that 0.52% -4.3% of mediastinal tumors were reported during the same period; Zhang Helin (1995) reported 10.74% in the same period, which may be related to the scope of hospital admission. It can be seen in the mediastinal and posterior mediastinal sulci, the latter being more common. Most are benign. Only about 10% are malignant. Paraganglioma is mostly "non-functional" but occasionally may be functionally active. The nerve secretion products are mainly norepinephrine, and there may also be trace amounts of epinephrine. The typical symptoms of pheochromocytoma can occur clinically, and massaging the tumor can increase blood pressure. Non-functional paraganglioma can display nerve secreted particles with electron microscope and cytochemical methods, and biochemical measurement can accurately quantify noradrenaline and epinephrine content (up to 24.5 & micro; g / g tumor tissue). When the content reaches 1.5mg / g, typical symptoms of pheochromocytoma can occur.

Most of pheochromocytomas are undoubtedly benign in terms of growth characteristics. However, because tumor cells often secrete a large amount of catecholamines, patients can die of hypertension and its complications. But it cannot be called malignant because of its lethality. Regarding the benign and malignant problems of pheochromocytoma, like other endocrine gland tumors, the morphology of tumor cells cannot be identified solely. One type is that the tumor cells have obvious atypia, with spindle-shaped, singular, deep-stained or huge multinucleated tumor cells, and more mitotic figures, but the biological behavior is neither infiltrated nor metastatic. In the opposite case, occasionally the morphology is well differentiated, but the transfer occurs unexpectedly. Or the tumor cells were locally infiltrated (invaded the envelope or blood vessels) but did not metastasize. Metastases mostly occur in the lungs, bones, lymph nodes, and brain. Metastatic lesions can sometimes show up years after the primary foci have been removed. Occasionally, the primary foci are concealed, and metastatic foci first show symptoms (such as intracranial metastases).

(Two) pathogenesis

Pathological manifestations:

1. Pheochromoparaganglioma cells are largely similar to their origin tissue. Small, non-enveloped, well-differentiated pheochromocytoma is sometimes difficult to distinguish from medulla hyperplasia. Tumor cells are usually irregularly polygonal, slightly larger than normal, rich in cytoplasm, granular, and sometimes empty, and the boundaries are not very clear. The nucleus is round or oval, often slightly deviated, the cytoplasm may be loose, but deep staining is not uncommon. Sometimes it is seen that the nucleoli is relatively large, and the tumor cells and nuclei may have a certain degree of abnormality, and mitosis is rare. Tumor cells can be dispersed and can be arranged in pseudoalveolar, bundle, trabecular or small pieces, and contain only a small amount of slender connective tissue, which is rich in blood vessels and often expands into sinusoids. Tumor cells are often accompanied by some smaller round cells, some of which may be naive pheochromoblasts or even sympathogenic cells, and some are lymphocytes. Sometimes tumor cells can further differentiate into more mature ganglion cells, showing small colonies, which can be accompanied by proliferation of neuron fibers and nerve sheath cells (Figure 1).

Occasionally a part of the tumor appears as a ganglioneuroma, a ganglioblastoma or a neuroblastoma. May also be accompanied by adrenal cortex adenoma.

2. Non-chromaffinous paraganglioma is visually manifested as an oval, slightly lobulated, elastic mass with a smooth surface and often close to the wall of large blood vessels. The capsule is often incomplete, especially in the carotid paraganglioma. The latter often have local infiltration. The section is gray-red to brown-red, and the blood vessels are very rich, sometimes similar to hemangiomas. Under the light microscope, images of endocrine gland tumors can be seen. It is composed of epithelial-like main cells arranged in a nest, and is separated by a rich and expanded fibrovascular interstitial that is sinusoidal. The peripheral part of the nest may have supporting cells (Figure 2), and nerve fibers are often difficult to see.

The main cells are light and dark. The bright cells are mostly polygonal. Rich in cytoplasm, transparent, with fine particles of chromaffin. The silver immersion method can show needle-sized chromaffin particles and the basement membrane network (vessels of the main cell nest). The nucleus is small or oval, and the nucleus is clear and transparent. Dark cells are small in size, dark in the cytoplasm, dark in the nucleus, inconspicuous nucleoli, and rarely seen in mitosis.

Under the electron microscope, the bright cells contained more neurosecretory particles. The boundary film is obvious and has a high electron density core. Dark cells contain only a small number of particles in some cells, the latter being relatively large and irregular. The ultrastructure of paraganglioma in different parts cannot be distinguished.

Malignant patients, like many endocrine gland tumors, are difficult to distinguish based on morphological features. The abnormality of tumor cells is not necessarily a sign of malignancy. The presence of necrosis and mitosis in the center of tumor cell nests, and infiltration of blood vessels and capsules can help speculate that it may be malignant.

Signs and symptoms of this paragraph 1. Non-pheochromocytopenic paraganglioma is mostly benign and usually asymptomatic. Mediastinal shadows are mostly found on physical examination, and the symptoms are mainly caused by tumor compression on surrounding organs.

2. Pheochromocytocytic paraganglioma is more common in young adults. The main symptoms are hypertension and changes in metabolism, which are easy to attract attention. Hypertension can be of two types: paroxysmal (emergency) and persistent. There is no difference between persistent and general hypertension. Patients may have palpitations, shortness of breath, chest depression, dizziness, headache, and sweating at the time of the attack. Sometimes nausea, vomiting, abdominal pain, and blurred vision. Some patients have symptoms such as nervousness, anxiety and fear, pale faces, cold limbs, and tremors. Sometimes the blood pressure can suddenly rise above 195mmHg (26.0kPa), and the onset usually lasts for several minutes to several hours, often accompanied by orthostatic hypotension. Persistent hypertension can eventually lead to malignant hypertension, and symptoms can only be relieved after tumor removal. Due to increased basal metabolism and decreased glucose tolerance, patients may have fever, weight loss, weight loss, and hyperthyroidism. In children, abdominal pain, constipation, sweating, blurred vision are more prominent, and some patients are usually asymptomatic.

It can be diagnosed based on medical history and clinical manifestations, combined with routine laboratory tests and X-ray and CT examinations. The final diagnosis requires pathological examination.

Edit this section to check the test Measure the elevated levels of catecholamines and their metabolites homovanillic acid (HVA) and vanillyl mandelic acid (VMA) in urine, often making the diagnosis.

1. The chest X-ray shows similar X-ray signs to other neurogenic tumors. The posterior mediastinal sulcus has shadows of different sizes, and it also shows that the tumor is over the ascending aorta and overlaps the spine, with a uniform density. The boundaries are clear. When the tumor cannot be distinguished from the aortic aneurysm or head and arm aneurysm, selective angiography can clearly show the origin of blood vessels. Tumor burrs can be seen in thoracic arteriography in 30% of cases, which is helpful to the diagnosis and localization of tumors before surgery.

2. CT scans showed that the masses near the anterior mediastinum aortic arch or posterior mediastinum were mostly solid, uniformly dense shadows, and sometimes cord-like dense shadows were connected to the aorta. Due to the abundant blood vessels of this tumor, CT-enhanced scanning of the tumor can obviously enhance the imaging.

3. Methyl iodophenylguanidine [131I-MIBG] scintigraphy has a significant effect on tumor localization, using MIBG scanning sensitivity of 85%.

4. MRI has certain value in diagnosing whether the paravertebral mass is a paraganglioma. Paraganglioma is shown as a non-homogeneous mass with a flowable substance inside. The latter is characterized by abundant blood vessels and fast blood flow.

Edit this paragraph treatment medication (a) treatment

1. Surgical resection should be the first choice for benign pheochromochromoparaganglioma and non-pheochromochromoparaganglioma. The risk of surgery is small, and the lesions can usually be completely removed. Surgical resection of its malignant paraganglioma is the ideal treatment. Surgical approaches and methods can refer to other mediastinal neurogenic tumors. When the tumor invades the heart, surgery under cardiopulmonary bypass is the preferred method. Tumor resection should be handled as appropriate, and it is not necessary to completely remove the tumor. If the tumor involves the coronary artery and the atrioventricular node Koch triangle, try to remove it. If the resection is complete, the prognosis is good.

2. Nearly 10% of patients have multiple paraganglioma, common in patients with a family history of endocrine tumor (MFN) syndrome and patients with Carney syndrome, gastric leiomyosarcoma, and extraadrenal paraganglioma. Therefore, after resection of the mediastinal paraganglioma, we should try to remove the paraganglioma in other parts in order to obtain better results.

Surgery of pheochromoparaganglioma has certain risks, and anesthesia and intraoperative blood pressure can fluctuate easily. Tumors are rich in blood vessels and are prone to bleeding close to large blood vessels, so it is extremely important to handle them properly before, during and after surgery. The blood volume of patients is usually lower than normal, and the effect is more significant when the pressure-increasing substance suddenly decreases when the tumor is removed. Therefore, a sufficient estimate should be made before surgery, and blood transfusion should be performed immediately before, during, and during surgery. Oral phenoxybenzamine (phenol benzylamine), an alpha-blocker before surgery can control blood pressure and then perform surgery, which can reduce blood pressure fluctuations during the operation. Try to make the anesthesia as smooth as possible during the operation, avoid squeezing the tumor, and prevent the hypertensive crisis caused by the pressure substance entering the blood due to inadvertent operation. If it happens, apply and adjust phenbenzamine (phenol benzylamine) azole in time. Intravenous dosage of morpholine, closely monitor the symptoms of chromaffin cells and chemoreceptors, and give timely treatment. If the tumor is rich in blood vessels, surgical resection has more bleeding, the risk is high, and bleeding cannot be controlled. If necessary, only a biopsy of the lesion can be performed to confirm the diagnosis. Regardless of whether the malignant lesion is completely removed or not, supplemental radiation therapy should be performed after surgery. Although such patients have metastases at about 30%, in these patients with metastatic lesions, -methyltyramine (a catecholamine blocker) Synthetic tyrosine hydroxylase inhibitors) help control symptoms.

(B) the prognosis

Non-pheochromic paraganglioma, benign patients have good postoperative results. Malignant disease accounts for about 10%. Olsen and Salyer (1978) reported that aortic body paraganglioma was invasive and often highly malignant. 50% of patients had severe disease at the time of detection, and the prognosis was poor after treatment. Death in the near future, pheochromochromoparaganglioma, benign tumor treatment is good. However, malignant lesions are prone to metastasis after surgery, or have concomitant symptoms or multiple lesions, so the prognosis is not good, which is often related to the control of concomitant symptoms and the thoroughness of resection of multiple lesions.