Diagnostic Cytopathology of Peritoneal Washings

Peritoneal washings used for cytologic evaluation are collected at the outset of surgical exploration of women with gynecologic cancers to assist in determining extent of disease and follow-up therapy. While there are similarities to ascites, these samples have differences that must be recognized in order to avoid false positive interpretations. Non-neoplastic mesothelial alterations including heterogeneous reactive changes, endosalpingiosis , endometriosis and tumor rupture are typically not seen in ascites samples but can be seen in peritoneal washings from women with malignancies that have not extended to the peritoneal cavity. Awareness of these potential pitfalls and knowledge of the associated tumor type will facilitate accurate interpretation. When these caveats are recognized, peritoneal washing cytology results are a useful adjunct in helping to determine patient follow-up in women with gynecologic malignancies.