Pseudoinvasive, nodular extramammary Paget's disease of the vulva

We report a case of recurrent extramammary Paget's disease of the vulva, which clinically, grossly, and microscopically mimicked an invasive lesion. A 76-year-old woman presented with recent onset of vaginal bleeding, a nodular vulvar lesion, and left inguinal lymphadenopathy. Following a vulvar biopsy and endometrial curettage, the patient underwent a total hysterectomy and bilateral salpingo-oophorectomy with lymph node dissection and a modified radical vulvectomy with left inguinal node dissection. Papillary serous adenocarcinoma was found involving the uterus and one right common iliac lymph node. Sections through the vulvar nodule revealed a marked intraepithelial proliferation, which resulted in a complex epidermal hyperplasia with deep invaginations. Tangential sections of rete pegs filled with Paget's cells and surrounded by papillary dermis displaced into the deep reticular dermis mimicked invasive nests of tumor cells. The loose fibrous tissue of the displaced papillary dermis resembled a desmoplastic reaction. No true stromal invasion was present, and none of the inguinal lymph nodes were involved by Paget's cells. The Paget's disease did not resemble the uterine carcinoma by histopathologic and immunohistochemical study. Recognition of the intraepithelial nature of Paget's disease has important clinical implications, inasmuch as stromal invasion can be associated with metastatic disease.