Adenomatoid Tumor Mimicking Peritoneal Carcinomatosis: A Case Report.

An adenomatoid tumor (AT) is a benign lesion, which is commonly located in the genital tract of both sexes. We present a case of a 66-yr-old woman with the unusual characteristics of an AT mimicking peritoneal carcinomatosis. The tumor was detected incidentally by ultrasound examination, and an ensuing imaging study raised suspicion of ovarian cancer with peritoneal carcinomatosis. From the pathologic diagnosis of frozen specimens, clear cell carcinoma was noted and the patient subsequently underwent cytoreductive surgery. An 8.5-cm-sized mass was observed on the uterine serosa, extending into the myometrium. In addition, multi-cystic nodular lesions were identified in the omentum, appendiceal and small bowel serosa, and the peritoneum. After histologic and extensive immunohistochemical examinations, the final diagnosis was AT. Recognition of the diverse presentations of AT is crucial for accurate diagnosis and appropriate treatment, as these tumors can involve multiple sites and mimic peritoneal carcinomatosis, potentially leading to a misdiagnosis of malignancy.