Polypoid endometriosis of the ovary and müllerianosis of pelvic lymph nodes mimicking an ovarian carcinoma with lymph node metastasis

Polypoid endometriosis is a distinctive variant of endometriosis with histological features simulating those of endometrial polyps. Mullerianosis is characterized by the presence of lesions at any site containing admixtures of endosalpingiosis, endometriosis, and endocervicosis. Here, we report a rare case of polypoid endometriosis of the ovary with mullerianosis of the pelvic lymph nodes in a 44-year-old woman without a past history of pelvic surgery. Magnetic resonance imaging revealed an ovarian tumor containing papillary nodules up to 3.0 cm in diameter and left pelvic lymph node enlargement. Nodules in ovarian tumor showed heterogeneous high intensity on T2-weighted image and high intensity on diffusion-weighted image and were mildly enhanced by gadolinium contrast material. Enlarged lymph node was markedly enhanced by gadolinium. We considered polypoid endometriosis in the differential diagnosis according to the results of the magnetic resonance imaging, and polypoid endometriosis was included in intraoperative consultation, however, ovarian carcinoma with lymph node metastasis could not be denied. According to histological examination, the final diagnosis was determined as polypoid endometriosis with glandular hyperplasia of the left ovary and mullerianosis in the obturator lymph nodes. To the best of our knowledge, this is the first report of polypoid endometriosis and mullerianosis of the pelvic lymph node.