Vasoactive intestinal peptide tumor
Introduction
Introduction to vasoactive intestinal peptide tumor Vasoactive intestinal peptide tumor (VIPoma) is a benign or malignant tumor of islet D1 cells, which causes severe watery water (Waterydiarrhea), hypokalemia (Hypopotassemia), stomach acid due to the secretion of a large amount of Vasoactive Intestinal Peptide (VIP) by D1 cells. Achlorhydria or Hypochlorhydria is also known as WDHA or WDHH syndrome. Secretory diarrhea is the most obvious symptom of this disease. The amount of watery diarrhea is large and lasts for a long time. Especially after 72 hours of fasting, the diarrhea is still not relieved and has diagnostic value. Secretory diarrhea is the most obvious symptom of this disease. The amount of watery diarrhea is large and lasts for a long time. Especially after 72 hours of fasting, the diarrhea is still not relieved. It has diagnostic value. Others include weight loss, abdominal cramps, skin flushing, etc. Laboratory examination, serum vasoactive intestinal peptide (VIP) determination, B-ultrasound, CT, selective pancreatic angiography and percutaneous transhepatic portal vein catheterization (PT-PC) and other positioning examinations are not difficult to make a diagnosis. In the location diagnosis of this disease, children should pay attention to the presence or absence of ganglioneuroma; at the same time, the adrenal gland should also be particularly vigilant to prevent missed diagnosis. basic knowledge The proportion of illness: 0.005% Susceptible people: no specific population Mode of infection: non-infectious Complications: hypercalcemia, kidney stones
Cause
Cause of vasoactive intestinal peptide tumor
Islet cell proliferation is one of the causes of VIPoma syndrome, which has a genetic predisposition.
Islet cell proliferation (45%):
Islet cells are classified into the following types according to their function of secreting hormones:
First, B cells ( cells), accounting for 60% to 80% of islet cells, secrete insulin, insulin can lower blood sugar. Lack of islet B cells will lead to diabetes.
Second, A cells ( cells), accounting for about 24% to 40% of islet cells, secrete glucagon, glucagon acts in contrast to insulin, which can increase blood sugar.
Third, D cells, accounting for 6% to 15% of the total number of islet cells, secrete growth hormone inhibitory hormone.
Genetic (30%):
The occurrence of this disease is related to heredity. If the parents or other relatives suffer from the disease, the offspring may cause the disease. Therefore, the occurrence of vasoactive intestinal peptide tumors has a great relationship with heredity.
Pathological change
The majority of vasoactive intestinal peptide tumors are single, isolated tumors with large differences in tumor size ranging from 1.5 to 10 cm in diameter. The tumor is located in the pancreas accounted for 84%, the rest are ganglioneuroma, neuroblastoma and ganglionoma; these tumors are distributed along the autonomic trunk and also in the adrenal gland, they all have the characteristics of VIPoma, and can secrete VIP.
In vasoactive intestinal peptide tumors located in the pancreas, 80% are single tumors and 20% are polycentric tumors. 75% are distributed in the pancreas and tail, and 25% are distributed in the head of the pancreas. 50% of pancreatic VIPomas are malignant tumors, and half of them have metastasized to the liver or surrounding lymph nodes at the time of diagnosis, and some have metastasized to the lungs, stomach or mediastinum. Most neurogenic VIPomas are benign, and only 10% are malignant. Islet cell proliferation is also one of the causes of VIPoma syndrome, and no tumor exists at this time.
Prevention
Vasoactive intestinal peptide prevention
(1) Develop good hygiene habits. Caregivers and children should wash their hands thoroughly with soap before and after meals.
(2) Guarantee the consumption of clean water.
(3) Do not eat spoiled food, the raw fruits should be washed.
(4) Strengthen physical exercise, enhance physical fitness, and exercise more in the sun. Excessive sweating can excrete acidic substances in the body with sweat, avoiding the formation of acidic constitution.
Complication
Vasoactive intestinal peptide tumor complications Complications, hypercalcemia, kidney stones
Hypophosphatemia, hypercalcemia, hyperglycemia, kidney stones and other symptoms.
Symptom
Vasoactive intestinal peptide tumor symptoms Common symptoms Secreted diarrhea Dehydrated glucose tolerance Reduced metabolic acidosis Gastric acid reduction Hypokalemia Hypophosphatemia Hypophosphatemia Calcium hypercalcemia Kidney stones
Secretory diarrhea is the most obvious symptom of this disease. The amount of watery diarrhea is large and lasts for a long time. Especially after 72 hours of fasting, the diarrhea is still not relieved. It has diagnostic value. Others include weight loss, abdominal cramps, skin flushing, etc. Laboratory examination, serum vasoactive intestinal peptide (VIP) determination, B-ultrasound, CT, selective pancreatic angiography and percutaneous transhepatic portal vein catheterization (PT-PC) and other positioning examinations are not difficult to make a diagnosis. In the location diagnosis of this disease, children should pay attention to the presence or absence of ganglioneuroma; at the same time, the adrenal gland should also be particularly vigilant to prevent missed diagnosis.
Diarrhea
The most prominent symptom of this disease is a large amount of secretory diarrhea. 70% of patients have more than 3L of diarrhea per day. The stool is thin like water. The appearance is brown, and the diarrhea is often sudden and violent, but in severe cases. The patient may have persistent diarrhea. After 48-72 hours of fasting in VIPoma patients, diarrhea continues to occur, so fasting for 72 hours is available for identification of diarrhea caused by other causes.
2. Water, electrolyte and acid-base balance disorders
Due to long-term persistent severe diarrhea, a large amount of electrolyte may be lost, the patient has dehydration to varying degrees, the circulating blood volume is decreased, the water of the pig, the hypochloremia, the metabolic acidosis, the electrolyte, the acid-base balance disorder; Severe patients can even lead to complications such as heart rhythm disorders, hypokalemia or renal failure, and even death.
3. Low stomach acid or no stomach acid
In 3/4 patients, the acidity of gastric juice is reduced, even without gastric acid. The mechanism is that vasoactive intestinal peptide can inhibit the secretion of gastric acid stimulated by pentagastrin gastrin, which can reduce gastric acid. Some patients can cause no gastric acid. Gastric mucosal biopsy revealed a normal number of parietal cells, further indicating that gastric acid reduction was not associated with changes in parietal cells themselves.
4. Hypophosphatemia and hypercalcemia
About 60% of patients will have hypophosphatemia, 50% of patients have hypercalcemia, and the mechanism of calcium and phosphorus metabolism disorders has not been fully elucidated. Because of high blood calcium after tumor resection, hypophosphatemia can be restored. Normal, it is speculated that it is associated with increased secretion of parathyroid hormones in the islet tumor itself.
5. Impaired glucose tolerance and hyperglycemia
About 50% of patients have impaired glucose tolerance, while those with elevated blood glucose are slightly less, about 18%. The reason is that the molecular structure of vasoactive intestinal peptide is very similar to glucagon, so glucagon may occur. The effect may also be the result of hypokalemia on islet function, and glucose tolerance may return to normal after tumor removal.
6. Other
About 62% of VIPome patients may have abdominal cramps; 20% of patients may have paroxysmal skin flushing, which often occurs in the face or chest; Bloom reports that 4% of patients have kidney stones, the mechanism remains unclear.
The disease takes about 3 years (2 months to 4 years) from the onset of symptoms to the diagnosis. It has also been reported for 15 years before the final diagnosis. Although the malignant VIPoma has often metastasized at the time of diagnosis, it is fatal. It is rare; death patients are often caused by severe diarrhea caused by water, electrolyte imbalance, and finally lead to arrhythmia or renal failure.
Examine
Examination of vasoactive intestinal peptide tumors
Laboratory examination
Dehydration, hypokalemia, hypochloremia, metabolic acidosis, low gastric acid, high blood calcium, low blood magnesium and glucose tolerance.
2. Determination of serum vasoactive intestinal (VIP)
The fasting serum VIP of normal people was 0-170pg/ml, with an average of 62±22pg/ml; the serum VIP of VIPoma patients was significantly increased, with an average of 956±285pg/ml, and also up to 2400pg/ml.
3. Positioning diagnosis
Since VIPoma itself is a rare disease, it is rare to systematically study the localization diagnosis method of this disease.
(1) B-ultrasound and CT: It can show the location, size and number of tumors, and whether there is liver or peripheral lymph node metastasis, so it is often used as the preferred positioning examination operation.
(2) Selective pancreatic angiography: can increase the accuracy and diagnostic rate of localization examination, but can also have false negative or false positive, and it is difficult to distinguish the specific type of islet tumor.
(3) Percutaneous transhepatic portal vein catheterization (PT-PC): The concentration of vasoactive intestinal peptide is measured by blood from the portal system of different sites, which is helpful to determine the location of the tumor.
(4) intraoperative B-ultrasound: helps to find small tumors located in the pancreas.
Diagnosis
Diagnosis and identification of vasoactive intestinal peptide tumor
1. Severe watery diarrhea should be differentiated from diarrhea caused by various other causes. The main ones are: 1 infectious diarrhea, diarrhea caused by bacterial infection is more urgent than the onset of secretory diarrhea in patients with vasoactive intestinal peptide tumor, stool mirror Detection or culture can detect pathogenic bacteria, while VIPoma patients have no pathogenic bacteria in the stool, 2 cholera or para-cholera, cholera onset is more urgent, such as rapid deterioration without treatment, fecal culture with cholera or Vibrio cholerae In patients with vasoactive intestinal peptide tumors, the course of disease can last for several months. In the past few years, there is no such bacteria in the culture of feces, and 3 osmotic diarrhea. Such diarrhea can be caused by food absorption disorder or excessive intestinal osmotic pressure, such as lactose malabsorption. Caused by other reasons, the identification of vasoactive intestinal peptide tumors can be carried out by fasting test. After 48-72 hours of fasting, the symptoms of osmotic diarrhea disappear; while secretory diarrhea persists, 4 other functional endocrine tumors There may also be diarrhea, but each has its own unique clinical manifestations that can be special.
2. Identification of vasoactive intestinal peptide tumor and gastrinoma: gastric acidosis in patients with gastrinoma, ulcer quality, low potassium content in feces, etc., can be distinguished from vasoactive intestinal peptide tumor; and gastrinoma patients After gastrointestinal decompression, diarrhea can often be eliminated, and vasoactive intestinal peptide patients have no change due to gastrointestinal decompression.
3. Identification of vasoactive intestinal peptide tumors and somatostatinoma: The latter is mainly caused by fatty sputum, which is significantly different from the watery diarrhea of the former.
4. Identification of vasoactive intestinal peptide tumors and carcinoids: carcinoid patients also have symptoms such as diarrhea and skin flushing, but their blood levels of serotonin and bradykinin are elevated, and urinary 5-hydroxyindoleacetic acid Increased (5-HIAA) levels are available for identification with vasoactive intestinal peptide patients.
