After sampling to rule out invasive disease, vaginal intraepithelial neoplasia (VAIN 3 lesions can be treated with laser or outpatient excisional therapy. Patients with vaginal intraepithelial neoplasia (VAIN 1 and most VAIN 2 and HPV infection do not require treatment. These lesions are multifocal and often regress, but may recur after ablative therapy.
Vulvar intraepithelial neoplasia, grade 3 (VIN 3), is treated by simple excision, laser ablation, or superficial (partial) vulvectomy, with or without split-thickness skin grafting. Excision of small foci of disease produces excellent results, and although multifocal or extensive lesions may be difficult to treat by this approach, it offers the most cosmetic result. VIN 1 or 2 is generally associated with dystrophic changes or HPV and can be managed expectantly.
Intraepithelial disease frequently occurs in the cervix, vagina, and vulva, and it may coexist in these areas. The cause and epidemiologic basis are common to all three locations, and treatment typically is ablative, excisional, and conservative. Early diagnosis and management are essential to prevent disease from progressing to invasive cancer.
The concept of preinvasive disease of the cervix was introduced in 1947, when it was recognized that epithelial changes could be identified that had the appearance of invasive cancer but were confined to the epithelium (1). Subsequent studies showed that these lesions, if left untreated, could progress to cervical cancer (2). Improvements in cytologic assessment led to the identification of early precursor lesions called dysplasia, a name that acknowledges the malignant potential of these lesions. Historically carcinoma in situ (CIS) was treated very aggressively (most often with hysterectomy), whereas dysplasias were believed to be less significant and were not treated or were treated by colposcopic biopsy and cryosurgery. The concept of cervical intraepithelial neoplasia (CIN) was introduced in 1968, when Richart suggested that dysplasias have the potential for progression (3). Most untreated CIN 1 and some CIN 2 lesions regress spontaneously; nevertheless, high-grade CIN refers to a lesion that may progress to invasive carcinoma when left untreated (4). Proliferating metaplasia without mitotic activity should not be called dysplasia or CIN because it does not progress to invasive cancer.
The criteria for the diagnosis of intraepithelial neoplasia may vary according to the pathologist, but the significant features are cellular immaturity, cellular disorganization, nuclear abnormality, and increased mitotic activity. The extent of the mitotic activity, immature cellular proliferation, and nuclear atypia identifies the degree of neoplasia. If the presence of mitoses and immature cells is limited to the lower third of the epithelium, the lesion usually is designated as CIN 1. Involvement of the middle and upper thirds is diagnosed as CIN 2 and CIN 3, respectively (Fig. 19.1).
Cervical Anatomy The cervix is composed of columnar epithelium, which lines the endocervical canal, and squamous epithelium, which covers the exocervix (5). The point at which they meet is called the squamocolumnar junction (SCJ) (Figs. 19.2 and 19.3).
Figure 19.1 Diagram of cervical intraepithelial neoplasia compared with normal epithelium.
The Squamocolumnar Junction