Significance of peritoneal washing cytopathology in ovarian carcinomas and tumors of low malignant potential: a quality control study with literature review.

OBJECTIVE: The author evaluated a consecutive group of peritoneal washings (PWs) performed in the evaluation of adnexal masses to determine whether the conventional histopathologic prognostic parameters significantly affect the tumor detection rate using this procedure. STUDY DESIGN: Cytopathologic reports from all PWs performed over a 13-year (1996-2008) period in the evaluation of malignant and borderline ovarian tumors were reviewed and correlated with those of the synchronously obtained histopathologic specimens. Tumors of low malignant potential (LMP) were separated for analysis. Statistical significance was determined using the χ2 test. RESULTS: In the study, a total of 134 PWs were associated with primary epithelial malignant tumors (n=114) or tumors of LMP (n=20) involving the ovary. The positive PW cytopathology rates for clear cell (83.3%), undifferentiated (80.0%), and serous carcinomas (65.7%) were higher than the overall average positive rate (62.3%) for all histopathologic subtypes. In contrast, endometrioid (41.2%) and mucinous (45.5%) carcinomas had markedly lower cytopathology-positive rates than the overall average positive rate (p=0.118). As expected, PWs were found to be significantly more likely to yield malignant cells in higher-grade (grades II+III, 71.1%, p=0.002) and higher-stage (stages III+IV) tumors (76.6%, p=0.000) than in lower-grade (grade I, 38.7%) and lower-stage (stages I+II) tumors (32.4%) and also in tumors with lymph node involvement (72.7%, p=0.021) than in tumors without lymph node involvement (46.7%) and in bilateral tumors (74.6%, p=0.004) than in unilateral tumors (42.9%). The positive cytopathology rates for the PWs of the corresponding primary ovarian carcinomas with prominent pleomorphism (81.0%, p=0.007), with high mitotic score (80.0%, p=0.006) and solid architecture (72.9%, p=0.122) were also higher than the overall average positive rate. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and efficiency for the ovarian carcinoma (n=114) cases were 72.3, 85, 95.8, 39.5 and 74.6%, respectively. The positive cytopathology rate for the PWs of the serous tumors of LMP (7.1%) was higher than that of the mucinous tumors of LMP (0.0%) and the overall average positive cytopathology rate (5.0%) for the ovarian tumors with LMP. The calculated sensitivity, specificity, PPV, NPV, and efficiency for tumors of LMP were 33.3, 100, 100, 89.5, and 90%, respectively. CONCLUSION: PW cytopathology results correlate significantly with almost all of the conventional histopathologic prognostic parameters and the cyto-histomorphologic parameters of the corresponding primary ovarian carcinomas. The positive cytopathology rates also differ according to the histopathologic subtypes. False negativity and 'false positivity?' was significantly correlated with tumor grade.