Extramammary Paget's disease and papillary thyroid carcinoma: two related or unrelated diseases?

Extramammary Paget’s disease (EPD) is a rare tumor occurs mainly in areas with numerous apocrine and or eccrine sweat glands. We report a 49-year-old woman who had referred to another hospital with the complaint of an erythematous and pruritic plaque on the vulva for 6 months. An incisional biopsy had been taken and pathological result was reported as invasive SCC. In her past medical history, there was a history of total thyroidectomy due to follicular variant of papillary thyroid carcinoma two years ago. The patient had been received radioactive iodine for 3 times, however her Iodine isotope scans were still positive. Then she was visited at our hospital for definite treatment. According to the pathologic report she underwent vulvectomy with inguinal lymph node dissection. Histological examination revealed primary invasive Paget disease of the vulva and there was one inguinal lymph node involvement. Second vision of the initial incisional biopsy was also compatible with primary invasive Paget disease of the vulva. We ruled out the possibility of metastatic deposits of thyroid carcinoma in the vulvar lesion and inguinal lymh node by IHC stains. Accurate classification of Paget's disease is essential for appropriate treatment. IHC stains are necessary to differentiate it from other tumors. The possibility of associated malignancy should be considered. To the best of our knowledge this case is the first case of primary Paget disease of the vulva in association with thyroid carcinoma.