ASCCP - Practice Recommendations - Practice Management Materials

PRACTICE RECOMMENDATIONS: Practice Management Materials

• Vulva • Vagina • Cervix • Anus

THE CERVIX: Premalignant Lesions of the Cervix: Spectrum of Disease

• I.	Introduction	• V.	Invasive Cancer of the Cervix
• II.	Anatomy of the Uterine Cervix	• VI.	Colposcopy
• III.	Histology of the Normal Cervix	• VII:	Cervical Cancer Screening and Colposcopy During Pregnancy
• IV.	Premalignant Lesions of the Cervix		Cervical Cancer Screening and Colposcopy During Pregnancy

It is well established that invasive carcinoma of cervix is preceded by a precursor lesion that morphologically resembles the adjacent invasive squamous carcinoma. This lesion is termed “carcinoma in situ” (CIS). However, CIS in itself is preceded by a spectrum of lesions with varying degrees of abnormality. The term “dysplasia” was introduced to refer to this spectrum of progressive cervical abnormality from normal epithelium to CIS. The word “dysplasia” means “abnormality of development.” Histologically, dysplasia is sub-classified into mild, moderate, or severe based on the extent to which the cervical epithelium is involved with abnormal cells: 1/3rd, 2/3rd or full thickness respectively. This classification reflects the biological potential of the precursor lesions to progress to invasive carcinoma. The majority of mild dysplasia lesions are of little if any malignant potential, but a few, perhaps 10%, will progress to a higher grade. At this time, it is not possible to distinguish which will progress clinically other than to watch over time. Moderate and severe dysplasias are considered true pre-malignant lesions with a progression rate to invasive cancer of 30% to 50% over time.

In 1960, the term “cervical intraepithelial neoplasia” (CIN) was introduced and implied the concept that precursor lesion to squamous cell carcinoma represented a single, continuous disease process. CIN nomenclature for histology is more specific to the cervix than the general term “dysplasia,” and makes clear the pre-invasive nature of lesions. The CIN nomenclature divides cervical cancer precursors into CIN1, CIN2, and CIN3, corresponding to mild, moderate and severe dysplasia/carcinoma in situ. It is the most widely used histologic terminology for cervical cancer precursors.

With the identification of human papilloma virus (HPV) as the etiologic agent for cervical cancer and its precursors in the 1980s, other more confusing terms became prevalent such as flat condyloma, atypical condyloma, condylomatous atypia, etc. appeared on cytology and histopathology reports. Our current understanding of the pathogenesis of cervical precursors is that that CIN is not a single disease process but rather represents two distinct entities: 1) a viral stage of productive infection which is usually self-limited and 2) neoplastic transformation in a minority of HPV-related lesions. This insight into the pathogenesis of CIN has revolutionized our understanding and approach to cervical disease. It also has lead to the development of a completely new nomenclature for cervical cytologic interpretation that better reflects this biologic process: the Bethesda System (1988, revised 1991, 2001). The Bethesda terminology for cytologic reporting subclassifies squamous cervical precursor lesions into low-grade squamous intraepithelial lesion (LSIL), for lesions previously classified as koilocytic atypia (HPV) and/ or CIN1, or high-grade squamous intraepithelial lesion (HSIL) encompassing CIN2 or 3 changes. Although originally introduced for cytologic reporting, the “SIL” terminology can be used for histologic classification as well, thus minimizing the confusion resulting from different terminologies for cytology and histology.