Histology Most cases of vulvar Paget’s disease are intraepithelial. Because these lesions demonstrate apocrine differentiation, the malignant cells are believed to arise from undifferentiated basal cells, which convert into an appendage type of cell during carcinogenesis (Fig. 19.21). The “transformed cells” spread intraepithelially throughout the squamous epithelium and may extend into the appendages. In most patients with an underlying invasive carcinoma of the apocrine sweat gland, Bartholin gland, or anorectum, the malignant cells are believed to migrate through the dermal ductal structures and reach the epidermis. In such cases, metastasis to the regional lymph nodes and other sites can occur.
Figure 19.20 Vulvar carcinoma in situ: carcinoma in situ (VIN 3) extending into the hair follicle.
Paget’s disease must be distinguished from superficial spreading melanoma. All sections should be studied thoroughly using differential staining, particularly periodic acid–Schiff (PAS) and mucicarmine stains. Mucicarmine has routinely positive results in the cells of Paget’s disease and negative results in melanotic lesion.
Clinical Features Paget’s disease of the vulva predominantly affects postmenopausal white women, and the presenting symptoms are usually pruritus and vulvar soreness. The lesion has an eczematoid appearance macroscopically and usually begins on the hair-bearing portions of the vulva (Fig. 19.22). It may extend to involve the mons pubis, thighs, and buttocks. Extension to the mucosa of the rectum, vagina, or urinary tract is described (142). The more extensive lesions are usually raised and velvety in appearance.
A second synchronous or metachronous primary neoplasm is associated with extramammary Paget’s disease in about 4% of patients, which is much less common than previously believed (143). Associated carcinomas were reported in the cervix, colon, bladder, gallbladder, and breast. When the anal mucosa is involved, there usually is an underlying rectal adenocarcinoma (139).
VIN The treatment of VIN 3 varies from wide excision to the performance of a superficial or “skinning” vulvectomy (144–147). Although the treatment originally recommended for CIS of the vulva was wide excision, fears that the disease is preinvasive led to the widespread use of superficial vulvectomy (146). Because progression is relatively uncommon, typically occurring in 5% to 10% of cases, extensive surgery is not warranted (144). This is particularly important because many VIN 3 lesions are found in premenopausal women.
The therapeutic alternatives for VIN 3 are simple excision, laser ablation, and superficial vulvectomy with or without split-thickness skin grafting.
CHAPTER 19 Intraepithelial Disease of the Cervix, Vagina, and Vulva
Figure 19.21 Paget’s disease of vulva. The epidermis is permeated by abnormal cells with vacuolated cytoplasm and atypical nuclei. This heavy concentration of abnormal cells in the parabasal layers is typical of Paget’s disease.
Excision of small foci of disease produces excellent results and has the advantage of providing a histopathologic specimen. Although multifocal or extensive lesions may be difficult to treat by this approach, it offers the potential for the most cosmetic result. Repeat excision is often necessary but can usually be accomplished without vulvectomy (145,147).
The carbon dioxide laser can be used for multifocal lesions but is unnecessary for unifocal disease. The disadvantages are that it can be painful and costly and does not provide a histopathologic specimen (148).