Clinical manifestations Small cell carcinoma of colon has no obvious symptoms in the early stage, but as the disease progresses, symptoms similar to those of colorectal cancer may appear, but bleeding is not as common as colorectal cancer and rarely causes intestinal obstruction. Some cases can secrete neurohormone peptide, which can cause some characteristic clinical symptoms also called carcinoid syndrome. Such as skin flushing, diarrhea, asthma, heart valve disease. Diagnosis In addition to history, symptoms, signs and pathomorphology, current studies have shown that immunohistochemical staining is of great significance in the diagnosis of small cell carcinoma of the colon: (1) cytokeratin has a discriminatory role as determining whether the tissue has an epithelial origin. (2) NSE has a high positive reaction rate in neuroendocrine tumors and is of diagnostic importance, and can be used as a common marker for the diagnosis of neuroendocrine tumors. (3) Cg-A is a more specific marker of neuroendocrine cells and tumors than NSE, which has been discovered only in recent years. (4) SYP is more specific than NSE in neuroendocrine tumors but has a lower positive response rate. Treatment Small cell carcinoma of the colon is highly malignant and prone to metastasis, but is more sensitive to chemotherapy. At present, for patients with clear diagnosis and no distant metastasis of small cell carcinoma of the colon, chemotherapy can be administered for 2-3 cycles before surgery to remove the tumor, followed by chemotherapy and radiotherapy. If the diagnosis is late, chemotherapy and radiotherapy will be the main treatment. Prognosis Small cell carcinoma of the colon is a highly malignant tumor with strong aggressiveness and early metastasis, especially liver metastasis. The lymph node and liver metastases are 60%-89% and 20%-71% respectively. The prognosis of this group of patients is very poor.