Detection of PAX8 and p53 is beneficial in recognizing metastatic carcinomas in pelvic washings, especially in cases with suspicious cytology

Objective: The aim of this study is to evaluate the detection of paired box gene 8 (PAX8) and p53 with immunohistochemistry in pelvic washing cell block sections. Methods: A total of 92 cases were used in this study, which were assigned to three groups according to the cytopathology files. The first group with positive cytology including endometrial and ovarian carcinomas comprised 32 cases. The second group with suspicious cytology for endometrial or ovarian carcinomas consisted of 29 cases. The third group with negative cytology (regarded as mesothelial cells) included 31 cases. The pelvic washing cell blocks underwent immunohistochemistry to detect PAX8 and p53 expression. Results: Immunoreactivity for PAX8 was found in 75% (24/32) of the cases in the group with positive cytology, in 6.9% (2/29) of the cases with suspicious cytology, and in none of the 31 cases with negative cytology (sensitivity: 75%; specificity: 100%; p < 0.05). p53 expression was detected in 37.5% (12/32) of the cases in the first group, in 3.4% (1/29) of the cases in the second group, and in none of the cases in the third group (sensitivity: 37.5%; specificity: 100%; p < 0.05). Moreover, the combined expression of PAX8 and p53 showed the same result as the single expression of p53 in the three groups. Conclusion: The detection of PAX8 and p53 is beneficial in recognizing metastatic carcinomas in pelvic washings, especially in cases with suspicious cytology, which additionally supports the Müllerian origin of these carcinomas.