Concurrent Primary Peritoneal Low-Grade Serous Carcinoma and Endometrial High-Grade Serous Carcinoma

A 64-yr-old postmenopausal woman with high-grade squamous intraepithelial lesion and atypical glandular cell of undetermined significance on her Pap test was found to have endometrial serous carcinoma (high grade) involving a polyp in a subsequent endometrial biopsy. She underwent hysterectomy and bilateral salpingo-oophorectomy with multiple biopsies of the peritoneum. Microscopic examination of the entirely submitted uterus showed no residual serous carcinoma. Multiple foci of low-grade serous tumor with extensive calcifications and psammoma bodies were identified on the surfaces of the left fallopian tube, ovaries, and biopsies of the peritoneum, consistent with peritoneal primary low-grade serous carcinoma. To our knowledge, this is the first reported case of low-grade serous carcinoma of the peritoneum with a concurrent (high-grade) serous carcinoma of the endometrium arising from an endometrial polyp.