Cervical CIN stands for: cervicalintraepithelialneoplasia, or cervical intraepithelial neoplasia, which is a precancerous lesion of the cervix. Etiology: Due to persistent infection with human papillomavirus (HPV), CIN is a collective term for a group of diseases that includes cervical atypical hyperplasia and cervical carcinoma in situ. Precancerous lesions are reversible for a considerable period of time, and it takes about 8 to 10 years, or even 20 years, to progress from precancerous to invasive stage. The concept of CIN was first introduced by Richart in 1967, and CIN was subdivided into CINI, CINII and CINIII, reflecting the evolution of cervical carcinogenesis. it was recognized in 1973 and incorporated into the collective term by the Bathasda (TBS) system in 1988. The precancerous lesions of the cervix (CIN) include cervical atypical hyperplasia and cervical carcinoma in situ, which are precancerous lesions of cervical invasive carcinoma, collectively called ClN, reflecting the pathological process of continuous development in cervical carcinogenesis, and have been more widely adopted by scholars at home and abroad. Pre-cancerous lesions of the cervix are not equal to cervical cancer. It takes about 10 years to develop from cervical precancerous lesion to cervical cancer through the process of cervical epithelial atypical hyperplasia → carcinoma in situ → invasive cancer, and treatment of cervical precancerous lesion should be early detection and early treatment. When the cervical epithelial chemotaxis is active, stimulated by certain foreign carcinogenic substances, or the migratory zone changes repeatedly, the active immature cells or proliferating squamous epithelium in the migratory zone may develop in the atypical direction: 1. Atypical hyperplasia: it means that the morphology of proliferating epithelial cells shows a certain degree of heterogeneity, but it is not enough to diagnose as cancer. Microscopically, the proliferating cells are of different sizes and morphologies, with large and densely stained nuclei, increased nucleoplasm ratio, increased nuclear fission but mostly normal nuclear fission; the cells are disorganized and disappear in the polar direction. If atypical hyperplasia is combined with human papillomavirus (HPV), the cancer rate is higher (high-risk HPV types 16, 18 and 33). 2. Cervical intraepithelial neoplasia (CIN): Atypical hyperplasia starts from the basal layer and gradually progresses to the superficial layer, if the whole epithelial layer is replaced by heterotypic cells, it is carcinoma in situ. According to the degree and extent of atypical hyperplasia, CIN is classified as grade I, II and III. CIN grade I (mild atypical hyperplasia): the heterogeneous cells are confined to the lower 1/3 of the epithelial layer. CIN grade II (moderate atypical hyperplasia): the heterotypic cells occupy 1/2 to 2/3 of the epithelial layer, and the heterotypicity is more obvious than grade I. CIN grade III (severe atypical hyperplasia and carcinoma in situ): heterotypic cells exceeding 2/3 of the epithelial layer are considered as severe atypical hyperplasia; those reaching the whole layer are considered as carcinoma in situ; heterotypy is more obvious than grade II, nuclear schizophrenic images are increased, and carcinoma in situ can appear pathological nuclear schizophrenic images. 3.Development and regression of lesions: Generally speaking, most of CINI grade can regress naturally, while part of CIN grade II may regress and another part progress to CIN grade III, and CIN grade III has a relatively high possibility of developing into cancer. 4.Cervical carcinoma in situ (CIS): It refers to the carcinoma of cervical epithelial cells. The heterogeneous proliferating cells involve the whole layer of cervical mucosal epithelium, but the lesion is confined to the epithelial layer and does not break through the basement membrane, and there is no infiltration in the interstitium.