It is not possible to determine whether a 10cm tumor of the sigmoid colon is malignant or not, pathological examination is the gold standard, in addition to other aspects to identify the benign or malignant. It is not possible to differentiate between benign and malignant tumors based on the size of the tumor, so it is not possible to determine whether a 10cm tumor in the sigmoid colon is benign or malignant based on the size of the tumor alone. Pathologic biopsy is the most accurate way to identify the tumor. In addition, there are other ways to determine the benign or malignant nature of the tumor. 1. Benign tumors: tumor cells are highly differentiated, grow slowly, have clear boundaries, do not infiltrate other tissues, and consume little to the body. 2. Malignant tumor: tumor cells with low differentiation, rapid growth, blurred boundaries, invasion of other tissues, and high consumption of the body. It is suggested that patients should go to regular hospitals for pathological biopsy, so as to make clear diagnosis as early as possible, give treatment as early as possible, reduce the damage caused by the disease to the body, and avoid delaying the aggravation of the disease.