151 Ovarian High-Grade Serous Carcinoma associated with a Continuum of Borderline Tumor and Low-Grade Carcinoma Components in a Young Female with BRCA1 Germline Mutation: A Rare Association

Introduction/Objective Ovarian serous carcinomas are classified into low-grade (LGSC) or high-grade (HGSC), based on morphology, supported by IHC. They generally have non-overlapping precursors, genomic profiles, and ages of presentation, but rarely co-exist. Methods/Case Report A 35-year-old underwent left salpingo-oophorectomy and staging for a 4.1 cm ovarian mass. Microscopically, the ovarian serous carcinoma showed a mixture of morphologic patterns, including low-grade monotonous nuclei with low mitotic index and wild-type p53; ambiguous grade nuclei with wild-type p53; and small area of high-grade nuclei with brisk mitoses and p53-mutated IHC. A focal serous borderline tumor (BOT) with low-grade cytology and wild-type p53 was also seen, associated with low-grade microinvasion. Small metastatic omental, small intestinal, sigmoid nodules and washings showed p53-mutated, HGSC morphology. WT1 was diffusely positive in all tumor areas. Fallopian tube was negative. NGS showed p53 mutation. Germline BRCA1 mutation was demonstrated. Results N/A Conclusion While rare, ovarian-origin HGSCs in association with BOT/LGSC have been reported, the latter tumor types are unexpected with germline BRCA1 mutation. Furthermore, this case is also unusual for the much younger age of presentation in a patient, detected during fertility treatment work-up.