Cytology of Benign Peritoneal Fluids and Pelvic Washing Specimens: Diagnostic Cytomorphologic Features and Pitfalls

Background: Pelvic washing and peritoneal fluid cytology specimens are used to detect peritoneal spread of malignancies. In most cases, identification of malignancy in these specimens is straightforward, but benign processes may occasionally mimic neoplasia and cause diagnostic difficulty. Summary: In this article, we perform a focused review of common benign entities encountered in pelvic washing and peritoneal fluid specimens during routine practice which may cause difficulty and discuss helpful features for avoiding diagnostic pitfalls. Key Messages: Application of strict cytomorphologic criteria, along with judicious use of ancillary studies and correlation with clinical, intraoperative, radiologic, and other pathologic findings, can help resolve most problematic cases.