The Use of Cytology Specimens in Isolation for Diagnosis of High-Grade Serous Carcinoma Prior to Initiation of Neoadjuvant Chemotherapy: A 3-Year Experience at a Large Referral Hospital

<b>Introduction:</b> Selected patients with pelvic high-grade serous carcinoma (HGSC) receive neoadjuvant chemotherapy prior to resection. Guidelines allow cytopathology fluids to be used to confirm this diagnosis before neoadjuvant chemotherapy, which can be less invasive and costly. This study examines how often cytology fluids are used for this purpose at our institution. <b>Methods:</b> Specimens of HGSC on cytology were searched for over 3 years. <b>Results:</b> Of 54 specimens, 44 of 54 (81%) were effusions, 10 of 54 (19%) were washings. The majority (32/54; 59%) of specimens were abdominal, the remaining were pleural (22/54; 41%). Most 32 of 54 (59%) were post therapy/diagnosis. A minority of specimens (14/54; 26%) had a concurrent surgical pathology specimen. In all, 34 of 52 (65%) patients were Stage 3, 13 of 52 (25%) Stage 4, and 5 of 52 (10%) Stage 2. Only 6 of 54 (11%) specimens were used solely for initial diagnosis with no concurrent surgical pathology specimen. All 6 were effusions; 5 of 6 (83%) were abdominal and 1 of 6 (17%) was pleural. Immunohistochemistry was performed on a majority (30/54; 56%) of specimens, with PAX8 being the most common, (30/54; 56%) and was positive in all specimens. Mutational p53 staining was noted in 20 of 21 (95%) specimens. <b>Conclusion:</b> Cytology fluid alone is uncommonly used for diagnosis of HGSC prior to initiation of neoadjuvant chemotherapy at our institution, possibly due to morphologic overlap on fluid specimens and relatively new implementation of neoadjuvant chemotherapy guidelines. High-grade serous carcinoma is most often encountered in effusions post-therapy. Morphology is similar in all specimens, regardless of preparation method or therapy status.