Rectal carcinoid tumors are usually slow-growing and, like benign tumors, the risk of metastasis is related to the size of the primary tumor. Rectal carcinoid tumor is curable in early stage, and the five-year survival rate can be more than 99% with surgery and tumor biotherapy techniques. Rectal carcinoid tumors, also known as amphiboles, occur in the mucosal glands of the intestine and account for 17%-25% of GI carcinoid tumors. Under colonoscopy, it appears as a grayish white or yellow hard raised mucosal and submucosal mass. The disease is a rare low-grade malignant tumor with localized infiltrative growth and little metastasis, and can secrete 5-HT, which causes “carcinoid syndrome” with typical symptoms of diarrhea, flushing, shortness of breath, cyanosis and right heart valve disease. What are the symptoms of rectal carcinoid tumor? 1. We should know that the symptoms of rectal carcinoid tumor lack special signs and symptoms, so it is quite difficult to diagnose. Clinically, it is often ignored or misdiagnosed as appendicitis, clonorchiasis, intestinal cancer and other diseases. When carcinoid tumor appears carcinoid syndrome, the diagnosis is easier. Typically, it presents with skin flushing, diarrhea, abdominal pain, asthma, right heart valve lesion and hepatomegaly. Increased serum 5-HT levels and increased urinary 5-HIAA excretion are significant for diagnosis, which can be established if they exceed 261.5 to 523 μmol/24h. Histological examination of the tumor can obtain the confirmation of the diagnosis. 2.The early symptoms of rectal carcinoid tumor are not obvious, and small carcinoid tumor can be asymptomatic, and mostly found accidentally during rectal finger examination or surgery. 3.Symptoms of rectal carcinoid tumor mostly occur in submucosa and deep mucosa layer, which are mostly yellowish or grayish yellow, with smooth and intact surface, clear border, hard texture, and generally small volume, most of which are less than 1.5cm in diameter, and occasionally larger than several centimeters. 4, some cases only show a limited submucosal thickening, flat and slightly concave plaque. Or polypoid lesions. It can grow directly by infiltration, or through lymphatic system or bloodstream metastasis. 5. With the progress of tumor, abdominal discomfort, diarrhea, constipation, change of stool habit, blood in stool, abdominal mass, low bowel obstruction and metastasis symptoms may appear. Diagnosis The diagnosis of carcinoid tumor is mainly based on histopathology and immunohistochemical analysis. Microscopically, tumor cells are morphologically consistent, mostly small round or polygonal in shape, and contain dense neuroendocrine granules. It is difficult to differentiate between benign and malignant microscopically because of the lack of common criteria for malignancy. Immunohistochemical analysis is a reliable tool for the diagnosis and differential diagnosis of carcinoid tumors. Chromogranin A (CgA) is a special component of the neuroendocrine granule matrix, which is a sensitive and specific marker to show neuroendocrine cells; the positive rate of Ki-67 is important to assess the proliferative activity of carcinoid tumor cells and judge the prognosis. The prognosis is better. Treatment 1.Endoscopic polyp resection of rectal carcinoid tumor is complete with no residual carcinoid tissue at the base and non-carcinoid tissue of 0.2 cm or more at each edge. 2.Endoscopic mucosal resection (EMR) is a safe and reliable treatment for rectal carcinoid tumor with diameter <1.0cm and confined to mucosal layer, and can preserve anal function. 3.Endoscopic submucosal dissection (ESD) endoscopic submucosal dissection resects large flat lesions, early cancers and submucosal tumors in the gastrointestinal tract and achieves better results. 4.Temporal endoscopic microsurgery (TEM) for rectal carcinoid tumor with diameter <2.0cm, infiltration depth not exceeding the submucosa layer and no lymph node metastasis, local resection by endoscopic microsurgery through the anus is feasible. If the tumor diameter is >2.0cm, lymph node metastasis, local excision reveals infiltration in the muscular layer, obvious ulcer on the surface, repeated local excision or other intestinal malignant tumors, radical excision should be performed according to the scope of radical rectal cancer. The clinical manifestation of rectal carcinoid tumor lacks specificity, rectal finger diagnosis and endoscopy can help early detection, histopathological and immunohistochemical analysis can confirm the diagnosis, and endoscopic resection is an effective method, and the prognosis mainly depends on early detection, early diagnosis and early treatment. With deeper understanding, newer medical devices and technological development, the treatment effect and prognosis of rectal carcinoid tumor will become better and better.