Carotid body tumor is a tumor from the tissue of the carotid glomus located in the bifurcation area of the carotid artery. It is more often benign, infiltrative growth and metastasis are less often observed. Scant clinical symptoms are characteristic, the only manifestation may be the presence of a tumor-like formation in the neck. There may be unpleasant sensations when swallowing and turning the head, dizziness, headache, voice changes and short-term fainting when pressing on the tumor. The diagnosis is established on the basis of complaints, examination data, ultrasound, CT, MRI and other studies. The treatment is operative.
General information
Carotid body tumor (chemodectoma) is a neoplasm originating from neuroendocrine cells, localized on the lateral surface of the neck, in the area of division of the common carotid artery. It belongs to the group of tumors of the APUD system. It is rarely diagnosed. Signs of malignancy, according to various data, are detected in 6-25% of cases. There is no correlation between the morphological structure of carotid body tumor cells and its clinical manifestations. A favorable course is possible in the presence of histological signs of malignancy. As the main criterion of malignancy, the features of symptoms (rapid growth, recurrence and metastasis) are considered.
The causes of carotid body tumor are unknown. Pathology can occur at any age, but more often affects patients 20-60 years old. Female patients predominate. Usually the tumor is detected on one side, less often it is bilateral. The disease can be detected in close relatives. Benign carotid body tumor are characterized by slow progression, cases have been described when such tumors have existed for 30 years or more. With malignancy, the prognosis is uncertain – some patients live for years or even decades, others die after a few years from multiple metastases. The treatment is carried out by specialists in the field of oncology, vascular surgery and neurosurgery.
Pathological anatomy
Carotid body tumor is a loose and soft, rarely dense round or oval tumor-like formation with a size of 0.5 to 5 centimeters or more. It originates from the carotid gland (carotid glomus) – the paraganglia, whose cells are presumably involved in the regulation of blood pressure and carbohydrate metabolism. It is located in the area of bifurcation of the carotid artery. There are four variants of the relationship between the carotid artery and carotid body tumor: the tumor is localized between the internal and external branches of the carotid artery; surrounds the internal branch of the carotid artery; surrounds the external branch of the carotid artery; covers the bifurcation zone and both branches of the carotid artery.
Carotid body tumor often “pushes” the branches of the carotid artery, increasing the angle of bifurcation. Infiltration of adventitia of the adjacent part of the vessel is observed, which complicates the surgical separation of the tumor and significantly increases the risk of surgical intervention. The carotid body tumor fits snugly to the sublingual, lingopharyngeal and vagus nerve, but there is no germination of the paraneurium. Large tumors spread into the maxillary space. Giant neoplasms can rise to the base of the skull and descend into the mediastinum.
Malignant carotid body tumor grow into the muscle tissue of the carotid artery wall. Over time, the vessel loses elasticity and turns into a rigid tube. Germination of nearby anatomical structures, metastasis to bones, regional lymph nodes and distant organs is possible. With the progression of the process, a conglomerate is formed, including adjacent nerves, the internal jugular vein, the pharynx and the sternocleidomastoid muscle. The color of benign carotid body tumor on the incision is pinkish-brown, malignant – with a grayish tinge. In the process of microscopic examination, large rounded or polygonal cells are found. The cells connect into glomeruli lying in the stroma. With malignancy, cellular atypia is detected.
Symptoms
In three out of four patients, the disease has been asymptomatic or asymptomatic for years. The reason for contacting an oncologist is the detection of a tumor-like formation on the side of the neck or an increase in the size of a long-existing tumor. Less often, patients with carotid body tumor complain of unpleasant sensations when swallowing or turning the head, soreness when pressing, pain radiating to the head, face and ear. Headaches and dizziness may occur due to a decrease in the lumen of the carotid artery. With the growth of carotid body tumor, progressive neurological disorders occur due to compression of nearby nerves.
Some patients have a history of blood pressure drops and short-term fainting states when pressing on the tumor. There may be hoarseness of voice, sudden attacks of weakness, a decrease in heart rate and lability of blood pressure. Sometimes patients with carotid body tumor develop mental disorders of the type of oncophobia. Palpation determines a soft or dense tumor-like formation, usually located above the angle of the lower jaw. The upper pole of the node may not be felt. Due to the close connection with the carotid artery, there may be a feeling of pulsation of the tumor.
Diagnostics
The diagnosis is established on the basis of anamnesis, complaints, external examination data and the results of instrumental studies. Patients with suspected carotid body tumor are referred for ultrasound duplex scanning of blood vessels, which allows to assess the structure, size and degree of vascularization of the neoplasm, as well as to determine the features of the location of the tumor in relation to the bifurcation and branches of the carotid artery. Multispiral CT is informative in determining the relationship between the carotid body tumor and neighboring anatomical structures, and can be used for differential diagnosis with some other diseases.
MRI with contrast allows you to get information about the location and structure of the carotid body tumor, its connection with nearby organs and the state of regional lymph nodes. At the final stage, selective carotid angiography is prescribed to determine the features of blood supply to the neoplasm. If necessary, this procedure can also be used for therapeutic purposes – for embolization of the vessels feeding the carotid body tumor. The final diagnosis is made taking into account the results of a cytological examination of a tissue sample obtained during a puncture biopsy.
Differential diagnosis of carotid body tumor is carried out with neoplasms of the thyroid gland, salivary glands, nerves, fascia, muscles and subcutaneous fat, with carotid artery aneurysm, with nonspecific lymphadenitis in chronic diseases of the oral cavity and ENT organs, with specific lymphadenitis in tuberculosis and syphilis, as well as with metastatic lesions of the lymph nodes of the neck.
Treatment
Therapeutic tactics are determined depending on the characteristics of the clinical course of the disease. In the absence of rapid growth and signs of malignancy, surgical intervention is not indicated even in the presence of a significant cosmetic defect, since due to the close connection of carotid body tumor with large vessels, any operation is associated with a high risk for the patient. With compression of the neck organs and chronic disorders of cerebral circulation caused by pressure on the arteries and a change in the position of the branches of the carotid artery, the neoplasm is removed. Vessels are preserved by carefully separating them from the tumor mass.
In the case when the discharge of the vessel is difficult, the external carotid artery is ligated. With a close fusion of a benign carotid body tumor with the carotid artery, partial exfoliation of the tumor with the preservation of the part of the capsule adjacent to the vessels is possible. In the malignant process, the tumor is removed, the bifurcation and branches of the carotid artery are resected and the affected vessels are replaced with a transplant. With benign neoplasms, nearby nerves, as a rule, can be preserved. In malignant carotid body tumor, the nerves are excised along with the altered tissues.
To be able to control the blood supply to the brain, surgical interventions are usually performed under local anesthesia. For large neoplasms, intubation anesthesia is used. Taking into account the risk of massive bleeding, operations are carried out after the preparation of a sufficient amount of blood, blood substitutes and anti-shock drugs. Radiotherapy and chemotherapy in the treatment of carotid body tumor are not used due to inefficiency.
The prognosis for benign neoplasms depends on the prevalence of the tumor, its connection with nearby anatomical structures and a number of other factors. Malignant carotid body tumor are considered as prognostically unfavorable. Life expectancy is determined by the degree of aggressiveness of local neoplasm growth and the rate of occurrence of distant metastases. Death may occur within a few years or decades after diagnosis.
