Peritoneal washing cytology of ovarian tumors of low malignant potential -: Correlation with surface ovarian involvement and peritoneal implants

OBJECTIVE: To correlate the cytologic diagnoses of peritoneal washings (PWs) with histologic findings of ovarian tumors of low malignant potential (LMP). METHODS: PW cytology from 90 patients with histologically confirmed ovarian tumors of LMP were reviewed and correlated with histologic findings. RESULTS: In 90 LMP tumor patients who underwent PW, cytologic diagnoses were reported as positive in 30 (33%) cases, atypical in 5 (6%) cases and negative in 55 (61%) cases. On review of the five atypical cases, three were reclassified as negative and two as positive. Peritoneal washings were positive in 20 (33%) of 60 patients with serous LMP tumors, 12 (44%) of 27 patients with mucinous LMP tumors and none of 3 patients with mixed LMP tumors. The presence of positive cytology was highly indicative of surface ovarian involvement or peritoneal implants in completely staged or selectively biopsied patients (P<.0001). Of 60 (67%) patients who had a staging laparotomy, positive PWs were seen in 3 (75%) of 4 cases with surface involvement only, 13 (94%) of 14 cases with peritoneal implants only, 3 (100%) of 3 cases with both peritoneal implants and ovarian surface involvement, and 9 (23%) of 39 cases without evidence of surface involvement or peritoneal implants. PWs were positive in 4 (13%) of 30 cases without staging laparotomy. CONCLUSION: PW cytology is a sensitive indicator of peritoneal dissemination of ovarian tumors of LMP. In addition, PWs will detect a high percentage of patients with subclinical intraperitoneal extension of such tumors and should be used routinely in the staging of ovarian tumors of LMP.