- The cervix often appears grossly normal.
- Infection with the human papillomavirus is present.
- Dysplastic or carcinoma in situ cells are noted in a cytologic smear preparation (traditional Pap smear or liquid-based cytology).
- Colposcopic examination reveals an atypical transformation zone with thickened epithelium, coarse punctate, or mosaic patterns of surface capillaries.
- Iodine-nonstaining (Schiller-positive) area of squamous epithelium is typical.
- Biopsy diagnosis of cervical intraepithelial neoplasia (dysplasia or carcinoma in situ).
Lower genital tract squamous intraepithelial neoplasia is often multicentric (ie, affecting multiple anatomic sites that embryologically are derived from the same anogenital epithelium): cervical intraepithelial neoplasia (CIN), vaginal intraepithelial neoplasia (VAIN, see Chapter 47), vulvar intraepithelial neoplasia (VIN, see Chapter 47), and perianal intraepithelial neoplasia (PAIN). Approximately 10% of women with CIN have concomitant preinvasive neoplasia of the vulva, vagina, or anus. Conversely, 40–60% of patients with VIN or VAIN have synchronous or metachronous CIN.
CIN, formerly called dysplasia, means disordered growth and development of the epithelial lining of the cervix. There are various degrees of CIN. Mild dysplasia, or CIN I, is defined as disordered growth of the lower third of the epithelial lining. Abnormal maturation of the lower two-thirds of the lining is called moderate dysplasia, or CIN II. Severe dysplasia, CIN III, encompasses more than two-thirds of the epithelial thickness with carcinoma in situ (CIS) representing full-thickness dysmaturity. While histologically evaluated lesions are characterized using the CIN nomenclature, cytologic smears are classified according to the Bethesda system, which was most recently revised in 2001. Briefly, atypical squamous cells are divided into those of undetermined significance (ASC-US) and those in which a high-grade lesion cannot be excluded (ASC-H). Low-grade squamous intraepithelial lesion (LSIL) encompasses cytologic changes consistent with koilocytic atypia or CIN I. High-grade squamous intraepithelial lesion (HSIL) denotes the cytologic findings corresponding to CIN II and CIN III. CIN may be suspected because of an abnormal cytologic smear, but the diagnosis is established by cervical biopsy. Spontaneous regression, especially of CIN I, occurs in a significant number of patients, allowing for expectant management with serial cytologic smears in the reliable patient. A certain percentage of high-grade lesions will progress to an invasive cancer if left untreated. Because it is not presently possible to predict which lesions will progress, it is recommended that all patients with CIN II and CIN III be treated when diagnosed. The only 2 exceptions to this recommendation concern adolescents, in whom CIN II may be followed, as spontaneous regression is substantial and the risk of cancer almost nil, as well as pregnant women, in whom treatment should be deferred to the postpartum period.
Prevalence figures for CIN vary according to the socioeconomic characteristics and geographic area of the population studied, from as low as 1.05% in some family planning clinics to as high as 13.7% in women attending sexually ...