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.