Morphologic Characteristics Seen in High-grade Serous Ovarian Carcinoma Metastases in Postneoadjuvant Chemotherapy Resections.

The morphologic features of metastatic high-grade serous ovarian carcinoma (HGSOC) after neoadjuvant chemotherapy have not been described. We conducted a 1-year retrospective, single-institution review of pretreatment biopsy and posttreatment metastases in cases of HGSOC treated with neoadjuvant chemotherapy. Two gynecologic pathologists and 1 pathology resident reviewed 11 cases looking for 6 morphologic features. We correlated these features with patient information on HRD abnormalities (HRD score, germline, and/or somatic BRCA mutations). When compared with the pretreatment biopsies of metastases taken at the time of diagnosis, the postneoadjuvant, treated metastases had unique morphologic findings, such as cytoplasmic vacuolization, cellular enlargement with eosinophilic cytoplasm, macro-nucleoli, cellular discohesion, and micropapillary architecture with abundant psammoma bodies. Metastases were also morphologically different from the primary site in the postneoadjuvant resection specimens.