Pathologic analysis is reliable in confirming the diagnosis of carcinoma in situ. Pathological analysis is to extract tissues from patients’ lesions and conduct cytological examination under microscope to observe the morphology of cells and cell nuclei to see whether there are abnormalities, which is a more important means to diagnose various types of carcinoma in situ and cancers, and is also regarded as the gold standard, and the result is relatively reliable. Besides pathological analysis, CT, MRI and other tests can also assist in the diagnosis of carcinoma in situ, only that they are not so high compared to pathological analysis, and pathological examination should be perfected after a high degree of suspicion. Once the diagnosis of carcinoma in situ is confirmed, it is necessary to carry out surgical resection in time, and the cure rate is still relatively high.