Carcinoid tumors can occur in any part of the digestive tract except the esophagus, and they are located in the appendix in 1/3 of cases, mostly in women, and rarely metastasize. The rest are located in the duodenum, colon (mostly in men), gallbladder and Merkel’s diverticulum, etc. It can also occur in the bronchi and ovaries, but is less common. In the small intestine, the malignancy is large and can metastasize to the lungs, bones and other intra-abdominal organs. Bronchial carcinoid tumors with carcinoid syndrome have a poor prognosis. Carcinoid tumors can occur at any age. Carcinoid tumors of the appendix occur mostly at the age of 30-40 years old, while carcinoid tumors of other sites occur mostly at the age of 50-60 years old. It should be distinguished from the following diseases: 1. Menopausal skin flushing It is a kind of skin flushing that lasts for a long time, but it is not serious and there is a feeling of skin fever. There is no skin cyanosis, no abdominal pain, diarrhea, wheezing and other symptoms. 2.Neurotic edema is a soft tissue limiting edema that occurs suddenly after various stimuli. It is an allergic angioneurotic edema, which often occurs in the face, lips, eyelids, and also in the mouth and throat; severe laryngeal edema may cause asphyxia. 3, systemic mastocytosis because of its increased production of histamine, causing skin flushing, skin mucous membrane can appear erythema, but also can have urticaria-like changes. It lasts for a long time and diarrhea may occur. When the skin is flushed, histamine in the blood increases. 4.Phytodysfunction When nervous, skin flushing can occur. However, the increase of 5-hydroxytryptamine in blood and 5-hydroxyindoleacetic acid in urine will not occur. 5.Diarrhea without skin flushing needs to be distinguished from diarrhea caused by other reasons, such as gastrinoma can cause ulcer disease and diarrhea. 6.When patients with carcinoid tumor have wheezing attacks, it should be distinguished from bronchial asthma. 7. Tricuspid valve lesions caused by carcinoid tumor should be distinguished from rheumatism, right ventricular papillary muscle dysfunction, and infective endocarditis.