There is a group of rectal tumors that are referred to as rare diseases by various medical and research centers, but have the same risk as rectal cancer. They are insidious in origin, difficult to diagnose at an early stage, have not been fully agreed upon in treatment, and their prognosis varies greatly among individuals. Among them, rectal neuroendocrine tumors and rectal mesenchymal tumors are the most typical. Rectal neuroendocrine tumors are epithelial-derived tumors, formerly known as “rectal carcinoid tumors”, and are a group of tumors that originate from endodermal neuroendocrine cells and have less neuroendocrine activity than neuroendocrine tumors in other parts of the digestive system. Mesenchymal tumors are mesenchymal-derived tumors and are often diagnosed as smooth muscle tumors or smooth muscle sarcomas because of the similarity of their microscopic morphology to smooth muscle tumors. Rectal neuroendocrine tumors can be divided into neuroendocrine tumors and neuroendocrine carcinomas, which have the characteristics of slow growth and long course, and can occur at any age, with middle and old age being the most frequent. In the early stage, there may be non-specific manifestations such as abdominal pain, diarrhea, change in stool habit or trait, or no symptoms at all. As mentioned above, neuroendocrine tumors of rectal origin rarely have neuroendocrine activity. Some patients show paroxysmal skin flushing, palpitations, watery diarrhea and other carcinoid syndrome manifestations, which mostly suggest advanced tumor and liver metastasis. Rectal mesenchymal tumor is usually found in middle-aged and elderly men, and the clinical symptoms are closely related to the volume of the tumor. When the tumor is small, it often has no clinical symptoms, but when the volume is large, it may cause difficulty in urination and frequent urination due to compression of the anterior urethra, or convexity to the rectal cavity, resulting in abdominal pain, change of stool habit or intestinal obstruction. Rectal neuroendocrine tumors are mostly manifested as submucosal protrusions into the intestinal cavity during rectal finger examination or colonoscopy, with broad-based or subtibial elevations, resembling polyps, covered by normal mucosa on the surface, and some of them may form ulcers with hard texture; endoscopic ultrasound shows well-defined isoechoic or hypoechoic masses, and can provide preoperative staging information to guide the development of surgical plans; serum CgA test and growth inhibitor test, which are more sensitive to neuroendocrine tumors, can be used to measure the neuroendocrine tumors. CgA test and growth inhibitor receptor scintigraphy, which are more sensitive to neuroendocrine tumors, are mostly negative in rectal-derived neuroendocrine tumors, but are more sensitive to progressive liver metastases, which can assist in preoperative staging and prognosis determination; CT and MRI have no specific diagnostic value for primary foci, but can be used to evaluate disease progression. Intraluminal ultrasound can reveal submucosal, slightly hard, round rectal wall exophytic masses; intracavitary ultrasound can reveal submucosal hypoechoic masses with clear borders in the rectal wall, or masses protruding from the rectal wall; CT and MRI can reveal well-defined masses in the rectal wall or protruding from the wall, and if intra-tumoral hemorrhage and necrosis are seen, it is more helpful for the diagnosis of mesenchymal tumor; CT and MRI can also evaluate the progression of mesenchymal tumor in the rectum. CT and MRI are also useful for evaluating the progress of rectal mesenchymal tumor. The preoperative diagnosis of neuroendocrine tumors and mesenchymal tumors still depends on pathological biopsy. The first choice of surgical treatment for rectal neuroendocrine tumors is determined by the size of the tumor and the depth of infiltration. A lesion with a diameter of <25px can be cured by endoscopic mucosal resection or mucosal dissection; a primary lesion with a diameter of 1-50px should be pathologically determined to be free of muscular infiltration before local excision, and radical surgery is required if there is muscular infiltration; patients with lesions >2cm in diameter should undergo radical surgery. Rectal neuroendocrine tumors are not very sensitive to radiotherapy, growth inhibitor receptor analogs and targeted therapy, and the efficacy is poor. Surgery is also preferred for rectal mesenchymal tumors, but the anatomy and physiology of the rectum are more complex than those of the stomach and small intestine, and the choice of mesenchymal resection is more varied, depending on the size of the tumor. It is generally accepted that smaller lesions can be locally resected, while larger lesions should undergo radical resection. Targeted drugs such as imatinib mesylate have shown significant efficacy in mesenchymal tumors, and it is now generally accepted that larger masses (>100 px) should receive adjuvant therapy with these drugs and then undergo radical surgery to preserve anal function after the tumor has shrunk in size. For patients with rectal mesenchymal tumors with risk factors, postoperative treatment should be supplemented with drugs such as imatinib mesylate. The prognosis of patients with rectal neuroendocrine tumors is generally good after early diagnosis and active treatment. In contrast, rectal mesenchymal tumors are prone to recurrence after surgery, but most of them are local recurrences, and most of the recurrent lesions still have the chance of surgical resection, and the recurrent lesions are still sensitive to targeted drug therapy, and the survival rate after recurrence surgery is still good. Therefore, as long as enough attention is paid to these two types of diseases, although rare but not terrible, early detection, early diagnosis, early treatment, will bring great benefits to patients.