Step 1: Extramammary Paget's disease (EMPD) is a rare, slow-growing intraepithelial adenocarcinoma that arises in skin bearing apocrine glands, outside the breast.
Step 2: In the female genital tract the classic site is the vulva, where it presents as a chronic eczematous, well-demarcated plaque and may be linked to an underlying adnexal or visceral adenocarcinoma.
Step 3: Therefore option A is correct. The vagina, cervix and uterus are lined by mucosa without the apocrine-rich skin in which Paget's disease typically develops.