Carcinoid

Carcinoid (argentaffinoma, chromaffinoma, carcinoid tumor, tumor of the APUD system) is a rare neuroepithelial hormonally active tumor that produces serotonin in excess. Carcinoids are formed in intestinal crypts from intestinal argentaffinocytes (Kulchitsky cells), which belong to the diffuse endocrine system.

The tumor occurs with a frequency of 1:4000 of the population, and according to pathological studies, the frequency of carcinoid tumors is 0.14%. Carcinoid tumors can be found in almost all organs and tissues. Carcinoid accounts for 5-9% of all tumors of the gastrointestinal tract. According to A. V. Kalinin (1997), carcinoid is localized in the appendix in 50-60% of cases, in 30% - in the small intestine. Much less often, carcinoid is localized in the pancreas, bronchi, gall bladder, ovaries and other organs.

The greatest amount of serotonin is produced by carcinoids localized in the jejunum, ileum and right half of the colon. When carcinoid is localized in the stomach, pancreas, duodenum, bronchi, the amount of serotonin produced by the tumor is significantly less.

For the first time, O. Lubarsch in 1888 gave a pathological description of tumor formations originating from these cells, later called argentaffin.

The name "carcinoid" was proposed by S. Oberndorfer in 1907 to designate a tumor of the intestine that is similar to a cancerous tumor (carcinoma), but differs from it in its lower malignancy. These tumors make up 0.05-0.2% of all malignant neoplasms and 0.4-1% of all neoplasms of the gastrointestinal tract. About 1-3% of them are localized in the large intestine, in some cases - in the vermiform appendix. Thus, according to J. Arid, in 5-8% of vermiform appendices removed due to chronic appendicitis, argentaffinoma is histologically detected. According to statistics by F. W. Sheely and M. H. Floch (1964), covering 554 descriptions of malignant tumors of the small intestine, carcinoids were observed in 65 cases (11.7%), which were most often localized in the distal section of the ileum. Rectal carcinoids have been described. These tumors are found in the bronchi, pancreas, liver, gall bladder, and prostate gland. They occur at any age, occasionally in childhood and adolescence (the average age of patients with this pathology is 50-60 years), approximately equally often in men and women.

Carcinoids are relatively slow-growing tumors. Therefore, due to the long absence of local symptoms, explained primarily by the small size of the tumors and their slow growth, carcinoids were long considered "almost innocent growths of the intestinal mucosa, an accidental finding during surgery or autopsy." Later, the malignancy of the tumor was proven, which, when localized in the small intestine, metastasizes in 30-75% of cases. In case of colon carcinoids, metastases are detected in 70% of cases; the 5-year survival rate is 53%. Most often, single and multiple metastases of carcinoid are described in regional lymph nodes, peritoneum, various parts of the intestine and liver.

The tumor is usually located in the submucosal layer of the intestine and grows towards the muscular and serous layer; its size is usually small, the diameter often varies from a few millimeters to 3 cm. On the section, the tumor tissue has a yellow or gray-yellow color, is characterized by a high content of cholesterol and other lipids, and is dense. With carcinoid, thickening and shortening of the tricuspid valve and pulmonary valve often occurs, and as a result - valve defect, muscle hypertrophy and dilation of the right ventricle.

Histological examination reveals the characteristic structure of a carcinoid tumor. The cytoplasm of the cells contains birefringent lipids and, most notably, grains containing serotonin, which are detected histologically using the chromaffin and argentaffin reactions.

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Causes of carcinoid development

The cause of carcinoid, like other tumors, is still unclear. It is noted that many symptoms of the disease are caused by the hormonal activity of the tumor. With the highest degree of reliability, significant secretion of serotonin (5-hydroxytryptamine) by tumor cells - a product of the conversion of the amino acid tryptophan, and its content in the blood reaches 0.1-0.3 μg / ml. Under the influence of monoamine oxidase, the bulk of serotonin is converted into 5-hydroxyindoleacetic acid, excreted in the urine. In the urine, the content of the final product of its conversion - 5-hydroxyindoleacetic acid (5-HIAA) - in carcinoid is sharply increased and in most cases is 50-500 mg (with a norm of 2-10 mg).

Cause of carcinoid

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Symptoms of carcinoid

The main symptoms of carcinoid are attacks of blood flow in the face, neck, chest - with the face, back of the head, neck, upper body suddenly turning red. In these areas, the patient feels a burning sensation, a feeling of heat, numbness. Many patients experience reddening of the eyes (conjunctival injection), increased lacrimation, hypersalivation, swelling of the face, tachycardia; a significant decrease in blood pressure is possible. At the onset of the disease, hot flashes are rare (1-2 times in 1-2 weeks or even in 1-3 months), later they become daily and can bother patients 10-20 times a day. The duration of hot flashes varies from one to 5-10 minutes.

Symptoms of carcinoid

Diagnosis of carcinoid

Laboratory tests in the vast majority of cases confirm an increased content of 5-hydroxytryptamine in the blood and 5-hydroxyindoleacetic acid in the urine, with the excretion of the latter in the amount of 12 mg/day being suspicious, and over 100 mg/day being considered a reliable sign of carcinoid. It should be taken into account that reserpine, phenathiazine, Lugol's solution and other medications, as well as eating large amounts of bananas and ripe tomatoes, increase the content of serotonin in the blood and the end product of its metabolism - 5-hydroxyindoleacetic acid in the urine, while chlorpromazine, antihistamines and other medications decrease it. Therefore, when conducting laboratory tests, one should keep in mind these possible effects on the test results.

Diagnosis of carcinoid

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Treatment of carcinoid

Surgical treatment - bowel resection with radical removal of the tumor and metastases, if any. Carcinoids of the colon, more often of the rectum, can also be removed through an endoscope or transanally. Symptomatic therapy consists of prescribing alpha- and beta-adrenergic receptor blockers (anaprilin, phentolamine, etc.); corticosteroids, chlorpromazine, and antihistamines are less effective.

Treatment of carcinoid

Prognosis for carcinoid

The prognosis with timely diagnosis and surgical removal of the tumor is relatively favorable, better than with other types of malignant tumors.

A characteristic feature of carcinoid is its slow growth, as a result of which the average life expectancy of patients even without treatment is 4-8 years or more. Death can occur from multiple metastases and cachexia, heart failure, intestinal obstruction.