Morphologic and Immunocytochemical Features of High-Grade Serous Carcinoma of Ovary in Ascitic Fluid Effusion and Fine-Needle Aspiration Cytology

Objectives: High-grade serous carcinoma (HGSC) is the most common ovarian malignancy. The role of cytopathology in obtaining tissue diagnosis before institution of neoadjuvant chemotherapy (NACT) was evaluated. Methods: All histopathology-proven HGSC specimens between 2015 and 2018 with prior cytopathologic diagnosis by ascitic fluid evaluation or fine-needle aspiration (FNA) of ovarian mass were reviewed with cell block immunocytochemistry for CK7, CK20, PAX8, WT1, and p53. Results: Of 288 cases of HGSC, pre-NACT cytology diagnosis was established in 32% (93/288), with specific HGSC diagnoses made on ascitic fluid in 88% (82/93) and by ovarian mass FNA in 12% ( 11/93). The ascitic fluid showed moderatelhigh cellularity with papillary clusters in 76% (71/93) cases. Cell block immunocytochemistry showed tunior cells positive for CK7, PAX8, and WT1. p53 showed mutant or null-type positivity in 65% (33/51) and 33% (17/51) of cases, respectively, with 100% concordance with subsequent histopathologv specimens Poor/intermediate response to chemotherapy was shown in 75% of cases. Conclusions: Combined assessment of cytomorphology, cell block histomorphology, and ancillary immunohistochemical testing, including PAX8, WT1, and p53, allows for specific pre-NACT diagnoses of HGSC in ascitic fluid and ovarian FNA cytology. This practice allows for initiation of chemotherapy and diminution of disease burden prior to definitive surgical therapy.