LAUSR

Background: Evaluation of peritoneal fluid cytology, either from ascitic fluids or as a result of peritoneal washings, is a fundamental aspect in the evaluation of women presenting with clinically concerning or histologically confirmed gynecologic neoplasms. Summary: Ascitic fluid samples are often the initial and only source of diagnostic material in women presenting with gynecologic malignancies, and important therapeutic decisions will result from the information provided in the cytology report. On the other hand, cytologic evaluation of peritoneal washing specimens obtained during surgical excision of a presumed gynecologic neoplasm provides crucial information to the clinical team regarding tumor staging, often with significant therapeutic implications. While recognition of high-grade tumors in either of these samples is generally straightforward, low-grade tumors and unusual neoplasms can prove to be more difficult to recognize, differentiate from benign mimics, and correctly diagnose, particularly in low-cellularity specimens. Even with high-grade tumors, a mere diagnosis of “positive for malignancy” in diagnostic ascitic fluid specimens might not suffice to guide clinical management, and the use of ancillary techniques to further and more definitively characterize the lesional cells is required. Key Messages: This review will focus on the clinically relevant issues surrounding interpretation of peritoneal fluid cytology specimens in the setting of gynecologic neoplasms, making emphasis on the salient cytomorphologic and immunocytochemical features of the various neoplastic processes, in an attempt to provide a practical yet effective guide on how to best evaluate, diagnose, and report these samples.