Pitfalls in Frozen Section: A Case of Incidental Papillary Mesothelioma.

Well-differentiated papillary mesothelioma is an uncommon benign, although potentially recurrent mesothelial lesion that occurs in the peritoneum of women over a wide age range. We recently encountered an incidental case sent for frozen section at the time of hysterectomy for endometrial carcinoma. Familiarity with this lesion will help prevent overinterpretation as a serous carcinoma.