Neuroendocrine tumor

Introduction to neuroendocrine tumors Neuroendocrine tumors are rare, accounting for less than 1% of all malignant tumors, mostly in the stomach, intestines, and pancreas. The most common type of cancer in this type of cancer is carcinoid, the incidence rate is about 2.5/100000, accounting for 50% of all gastrointestinal pancreatic neuroendocrine tumors. According to the origin of the site, the carcinoid can be divided into the foregut (lung, The bronchus and the upper gastrointestinal tract of the jejunum, the midgut (ileum and appendix) and the hindgut (rectal and rectum), such tumors can occur throughout the neuroendocrine system, but the most common site of involvement is the pancreas. Neuroendocrine tumors can be divided into two broad categories based on whether the substances secreted by the tumor cause typical clinical symptoms - functional and non-functional. basic knowledge Sickness ratio: 0.0001% Susceptible people: no special people Mode of infection: non-infectious Complications: thrombocytopenia

Neuroendocrine tumor etiology

Genetic factors (75%)

The cause is still unknown. However, studies have shown that the disease has a certain hereditary nature. Because about half of the children of neuroendocrine tumor patients can suffer from this hereditary disease, screening is important for early diagnosis and treatment. Recently, the abnormal pathogenic genes of IIA and IIB have been clarified. Detection of abnormal genes can ultimately lead to earlier, more effective diagnosis and treatment.

Pathogenesis

The cause of this disease has not yet been elucidated. A neuroendocrine tumor is a tumor that produces small molecular peptides or peptide hormones, namely apud cell tumors, which can act by increasing the cyclic adenine monophosphate by target cells and secrete serotonin with strong physiological activity (5). - serotonin), vasopressin and histamine, and some hormones that secrete other peptides, such as adrenocorticotropic hormone, catecholamines, growth hormone, parathyroid hormone, calcitonin, anti-urea, gonadotropin Hormones, insulin, glucagon, prostaglandins, gastrin, motilin and other substances. The main substances that produce carcinoid syndrome are serotonin and bradykinin, and histamine is also involved in some of the effects.

Serotonin has a direct contraction effect on peripheral blood vessels and pulmonary blood vessels, and also has a strong contraction effect on the bronchus. It has a stimulating effect on the vagus nerve and ganglion cells of the gastrointestinal tract, and the gastrointestinal tract peristalsis is enhanced and the secretion is increased.

Bradykinin has a strong vasodilator effect, and some carcinoid tumors, especially gastric carcinoids, can produce a large amount of vasoactive substances such as bradykinin and histamine, which cause skin flushing. Increased serotonin in the circulation can also cause endocardial fibrosis.

Under normal circumstances, only about 2% of the tryptophan ingested in food is used for the synthesis of serotonin (5-ht), and 98% enters the metabolic pathway of niacin and protein synthesis. However, in patients with carcinoid syndrome, 60% of tryptophan can be taken up by tumor cells, resulting in increased 5-ht synthesis and reduced niacin synthesis. 60% of the tumor cells ingested tryptophan catalyzed by tryptophan hydroxylase to 5-hydroxytryptophan (5-htp), and then converted to 5-ht by dopa decarboxylase, partially stored in the secretion of tumor cells. Inside the granules, the rest goes directly into the blood. Most of the 5-ht free in the blood is degraded into 5-hydroxyindoleacetic acid (5-hiaa) through the monoamine oxidase (mao) in the liver, lung, and brain, and is excreted from the urine. The level of 5-ht in the serum of carcinoid patients originating from the midgut system is increased, while the 5-hiaa excretion in the urine is increased. This is a typical carcinoid syndrome. This category accounts for more than 75% of cases of carcinoid syndrome. The carcinoid of the foregut system often lacks dopa decarboxylase and cannot convert 5-htp to 5-ht. 5-htp is directly released into the blood, so the 5-htp level in the patient's serum is elevated, while 5-ht is not Raise. The 5-htp and 5-ht excretion in the patient's urine increased, while the 5-hiaa increase was not obvious, which is atypical carcinoid syndrome.

Neuroendocrine tumor prevention

The disease has a certain hereditary nature, so early screening is very important. Because about half of the children of neuroendocrine tumors can develop this genetic disease, screening is important for early diagnosis and treatment. Detection of each tumor is usually useful. Recently, the abnormal pathogenic genes of IIA and IIB have been clarified. Detection of abnormal genes can ultimately lead to earlier, more effective diagnosis and treatment.

Multiple skin metastases metastasized through the blood or lymphatic vessels suggest that the disease course is advanced and the survival period is 3 to 12 months.

Neuroendocrine tumor complications Complications thrombocytopenia

Blurred vision, thrombocytopenia.

Neuroendocrine tumor symptoms Common symptoms Gastric acid deficiency Fat painful red tongue and lip chapped thrombocytopenia telangiectasia

Functional neuroendocrine tumors often present with corresponding symptoms caused by excessive secretion of tumor-associated substances.

1. Carcinoid syndrome: Sudden or persistent head and face, flushing of the trunk skin, may be induced by alcohol, strenuous activity, mental stress or eating foods containing 3-p-hydroxyaniline such as chocolate, banana, etc.; mild or Moderate diarrhea, diarrhea does not necessarily coincide with skin flushing, may be associated with increased bowel movements, may be associated with abdominal pain; carcinoid-related heart disease, such as pulmonary stenosis, tricuspid regurgitation, etc.; other symptoms such as skin capillaries Dilatation, pellagra, etc., occasional dermatitis, dementia and diarrhea.

2, gastrinoma: often manifested as Zollinger-Ellison syndrome, abdominal pain, common diarrhea, intermittent diarrhea, often fat phlegm, but also recurrent peptic ulcer.

3, insulinoma: The clinical symptoms are related to the excessive secretion of insulin by tumor cells. The characteristic manifestation is neurohypoglycemia, which is common in the morning or after exercise, and other manifestations such as blurred vision and mental abnormalities.

4, glucagonoma: often accompanied by excessive glucagon secretion, typical manifestations of necrotic migratory erythema with anemia and thrombocytopenia, about half of patients may have moderate diabetes, may also be painful Red tongue, chapped lips, venous thrombosis, intestinal obstruction and constipation.

5, VIP tumor: typical symptoms are Verner-Morrison syndrome, that is, pancreatic cholera syndrome, manifested as watery diarrhea, hypokalemia, gastric acid deficiency and metabolic acidosis.

Non-functional neuroendocrine tumors often lack typical clinical manifestations, and liver metastases often appear at the time of presentation.

Neuroendocrine tumor examination

It can be used for the diagnosis and monitoring of tumor treatment effects by measuring chromaphilic peptide A and pancreatic polypeptide.

Special staining and immunohistochemistry: carcinoid from the bronchus, silver-positive silver-positive particles, positive for silver staining, small intestinal carcinoids containing Fontans-Masson-positive silver-stained particles, immunoperoxidase test, neuroblasts Small circular basophils are positive for neuron-specific enolase (NSE) and neurofilament, and stromal spindle cells S-100 protein positive suggests that their cells differentiate like Schwann cells, and Merkel cell carcinoma has nerves. Both endocrine and epithelial differentiation are characterized by unique spheroidal staining near the paranuclear and nucleus, similar to cytoplasmic inclusions and small dots around the nucleus, using low molecular weight keratin antibodies such as AE-1, CAM-5.2 and Neurofilament staining showed that Merkel cell carcinoma epithelial membrane antigen, chromogranin, neurofilament and NSE staining were also positive, but S-100 protein, carcinoembryonic antigen and leukocyte common antigen staining were negative, lung metastasis Small cell carcinoma stained with low molecular weight cytokeratin showed a diffuse perinuclear spot appearance, stained with anti-neurofilament antibody to a lesser degree, although Merkel cancer was stained with CEA. The reaction, but about 50% of small cell carcinoma metastatic CEA staining positive reaction, papillary and follicular thyroid carcinoma, thyroglobulin positive immunostaining, medullary thyroid cancer, calcitonin staining.

Diagnosis and diagnosis of neuroendocrine tumors

Neuroendocrine cancers are classified into carcinoid (highly differentiated), atypical carcinoid (medium differentiation), and small cell carcinoma (lowly differentiated).

First, according to clinical manifestations, it is divided into qualitative diagnosis (detection of specific abnormal secretion hormone levels) and localization diagnosis (various imaging examinations). In the detection of various biochemical indicators, urinary 5-hydroxyindoleacetic acid (5-HIAA) has a sensitivity of 70% for carcinoid diagnosis and a specificity of 90%. Elevated 5-HIAA levels in urine are closely related to tumor size and the severity of carcinoid heart disease, and are not related to the severity of carcinoid syndrome, and the relationship between the occurrence and prognosis of diarrhea is not clear. When performing a 24-hour urine 5-HIAA measurement, care should be taken to place the urine in a refrigerator or in a cool place to avoid errors.

Chromogranin A (CgA) levels are specific markers of neuroendocrine tumors (NET) and are most commonly used clinically. There is also a slight increase in CgA in normal or non-neuroendocrine tumors, but at a lower level. The sensitivity of serum CgA is related to tumor type, degree of differentiation and size. The results of different laboratories may also vary.

For patients with suspected NET but mildly elevated hormone levels, a secretin stimulation test is recommended with a sensitivity of 80%, while the sensitivity of the calcium stimulation test is only 40%.

Imaging studies are the primary method of localization diagnosis and can also monitor response to treatment. Currently, CT, magnetic resonance imaging (MRI), ultrasonography (US), endoscopic ultrasound (EUS) and other tests have not been further evaluated. The sensitivity of somatostatin receptor imaging may vary depending on the type of tumor, which is more than 75% sensitive to pituitary tumors, gastrointestinal pancreatic neuroendocrine tumors, but only moderately sensitive to insulinomas (40) %~75%).

NET diagnosis requires tissue biopsy and pathology detection, mainly to detect specific markers of NET, and Ki67 (a proliferating cell-associated nuclear antigen) test helps to determine the degree of proliferation and disease stage.

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