For example, it is considered proven that the development of vascular disorders in carcinoid syndrome is caused by the interaction of serotonin and catecholamines (Menshikov V.V. et al., 1972). Cases of a combination of carcinoid syndrome with acromegaly and hypercortisolism have been described. It is possible that this combination is due to the ability of carcinoid tumor cells to produce GH- and ACTH-like substances. Under the influence of high concentrations of serotonin, endothelial tissue fibrosis develops, smooth muscle contraction occurs, which causes a narrowing of the arteries.
Damage to the cardiovascular system due to hyperserotoninemia in carcinoid syndrome is reduced to the development of tricuspid valve insufficiency and pulmonary artery stenosis, as well as fibrosis of the endocardium of the right atrium and right ventricle. Narrowing of arterioles leads to the development of arterial hypertension. Carcinoid tumors are classified as arising from the anterior intestinal tube (bronchi, stomach, duodenum, bile ducts, pancreas), middle intestinal tube (jejunum, ileum, appendix, ascending colon), posterior intestinal tube (transverse colon). colon, descending, sigmoid and rectum).
Sometimes they are also found in the gonads, prostate, kidneys, mammary glands, thymus gland or skin.
The most characteristic changes in the blood picture in carcinoid syndrome are acceleration of ESR and leukocytosis, and a direct relationship is determined between blood changes and the occurrence of crises. Carcinoids, especially bronchial carcinoids, can secrete ACTH, which causes Cushing's syndrome, growth hormone-releasing hormone, which causes acromegaly.
The diagnosis is confirmed by the high content of sorotonin in the blood plasma, increased urinary excretion of 5-hydroxyindoleacetic acid, as well as the detection of intestinal, liver, and lung tumors during instrumental research methods. Biochemical parameters can be distorted when consuming foods containing large amounts of serotonin (bananas, walnuts, citrus fruits, kiwi, pineapples), taking rauwolfia preparations, phenothiazines, salicylates, as well as in pathological conditions complicated by intestinal obstruction, when the excretion of 5-hydroxyindoleacetic acid may increase to 9-25 mg/day.
Immunofluorescence studies confirm the presence of neuropeptides (serotonin, substance P and neurotensin) in carcinoid tumors. Determination of carcinoembryonic antigen (CEA) in the diagnosis of carcinoid tumorsx tumors also makes some sense. its level is usually normal or minimal. If the CEA concentration is elevated, another tumor should be suspected. Comprehensive topical diagnosis of carcinoids involves X-ray examination, computed tomography, ultrasound scanning, the use of immunoautoradiographic methods for determining hormones in the blood, selective arterio- and venography, scintigraphy with indium-111-octreotide and morphological examination of the biopsy specimen. The use of the entire complex of modern research methods (fluoroscopy, endoscopy, selective arterio- and phlebography, ultrasound, computed tomography, radionuclide studies, determination of hormones in the blood, immunohistochemical study of tumor biopsies) ensures the correct diagnosis in 76.9% of cases.
Considering the general principles of therapy for carcinoid syndrome, it should be noted that the earliest possible removal of the tumor is advisable. However, it must be remembered that clinical manifestations of carcinoid syndrome very often occur in cases where there are already functionally active metastases in the liver. In this case, radical surgical treatment is not feasible.
