Cervical intraepithelial neoplasia
|Cervical intraepithelial neoplasia|
|Classification and external resources|
Cervical intraepithelial neoplasia (CIN), also known as cervical dysplasia and cervical interstitial neoplasia, is the potentially premalignant transformation and abnormal growth (dysplasia) of squamous cells on the surface of the cervix. CIN is not cancer, and is usually curable. Most cases of CIN remain stable, or are eliminated by the host's immune system without intervention. However a small percentage of cases progress to become cervical cancer, usually cervical squamous cell carcinoma (SCC), if left untreated. The major cause of CIN is chronic infection of the cervix with the sexually transmitted human papillomavirus (HPV), especially the high-risk HPV types 16 or 18. Over 100 types of HPV have been identified. About a dozen of these types appear to cause cervical dysplasia and may lead to the development of cervical cancer. Other types cause warts.
The earliest microscopic change corresponding to CIN is dysplasia of the epithelial or surface lining of the cervix, which is essentially undetectable by the woman. Cellular changes associated with HPV infection, such as koilocytes, are also commonly seen in CIN. CIN is usually discovered by a screening test, the Papanicolaou or "Pap" smear. The purpose of this test is to detect potentially precancerous changes. Pap smear results may be reported using the Bethesda System. An abnormal Pap smear result may lead to a recommendation for colposcopy of the cervix, during which the cervix is examined under magnification. A biopsy is taken of any abnormal appearing areas. Cervical dysplasia can be diagnosed by biopsy.
Some risk factors that have been found to be important in developing CIN are:
- Women who become infected by a "high risk" type of HPV, such as 16, 18, 31, or 45
- Women who are immunodeficient
- Women who give birth before age 17
Depending on several factors such as the type of HPV and the location of the infection, CIN can start in any of the three stage, and can either progress, or regress.
CIN is classified in grades:
|Histology Grade||Corresponding Cytology||Description||Image|
|–||–||Normal cervical epithelium|
|CIN 1 (Grade I)||LSIL||The least risky type, represents only mild dysplasia, or abnormal cell growth. It is confined to the basal 1/3 of the epithelium. This corresponds to infection with HPV, and typically will be cleared by immune response in a year or so, though can take several years to clear.|
|CIN 2/3||HSIL||Formerly subdivided into CIN2 and CIN3.|
|CIN 2 (Grade II)||Moderate dysplasia confined to the basal 2/3 of the epithelium|
|CIN 3 (Grade III)||Severe dysplasia that spans more than 2/3 of the epithelium, and may involve the full thickness. This lesion may sometimes also be referred to as cervical carcinoma in situ.|
CIN 1 does not require treatment if it lasts less than 2 years. Treatment for higher grade CIN involves removal or destruction of the neoplastic cervical cells by cryocautery, electrocautery, laser cautery, loop electrical excision procedure (LEEP), or cervical conization. Therapeutic vaccines are currently undergoing clinical trials. The lifetime recurrence rate of CIN is about 20%, but it isn't clear what proportion of these cases are new infections rather than recurrences of the original infection.
Between 250,000 and 1 million American women are diagnosed with CIN annually. Women can develop CIN at any age, however, women generally develop it between the ages of 25 to 35.
- Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; & Mitchell, Richard N. (2007). Robbins Basic Pathology (8th ed.). Saunders Elsevier. pp. 718–721. ISBN 978-1-4160-2973-1.
- Cervical Dysplasia: Overview, Risk Factors
- Agorastos T, Miliaras D, Lambropoulos A, Chrisafi S, Kotsis A, Manthos A, Bontis J (2005). "Detection and typing of human papillomavirus DNA in uterine cervices with coexistent grade I and grade III intraepithelial neoplasia: biologic progression or independent lesions?". Eur J Obstet Gynecol Reprod Biol 121 (1): 99–103. doi:10.1016/j.ejogrb.2004.11.024. PMID 15949888.
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- Park J, Sun D, Genest D, Trivijitsilp P, Suh I, Crum C (1998). "Coexistence of low and high grade squamous intraepithelial lesions of the cervix: morphologic progression or multiple papillomaviruses?". Gynecol Oncol 70 (3): 386–91. doi:10.1006/gyno.1998.5100. PMID 9790792.
- Wright TC, Jr; Massad, LS; Dunton, CJ; Spitzer, M; Wilkinson, EJ; Solomon, D; 2006 American Society for Colposcopy and Cervical Pathology-sponsored Consensus, Conference (2007 Oct). "2006 consensus guidelines for the management of women with cervical intraepithelial neoplasia or adenocarcinoma in situ.". Journal of lower genital tract disease 11 (4): 223–39. PMID 17917567.