Ovarian Serous Carcinoma With a Novel HSP90AB1 Mutation in a Patient With Synchronous Primary Fallopian Tube Serous Carcinoma

Background/Aim: Ovarian carcinoma is the fifth leading cause of cancer-related deaths in women in the United States. Serous papillary carcinoma is the most common histological type of ovarian carcinoma that often goes undetected until it has spread within the pelvis and abdomen leading to poor prognosis. Translation of next-generation sequencing (NGS) technology into personalized medicine and identification of new potential targets for therapeutic applications may be helpful. Case Report: We report a case of a 59-year-old female who initially presented in the emergency department with increasing abdominal girth, and bloating. Computed tomography showed ascites and omental and pelvic masses. Fine needle biopsy of the omental mass showed highgrade papillary adenocarcinoma consistent with high-grade ovarian serous carcinoma. She was treated with chemotherapy followed by debulking surgery. Primary ovarian serous carcinoma and synchronous primary fallopian tube serous carcinoma with multiple leiomyomas were identified in the surgical specimen. Pleural biopsy was also positive for carcinoma. NGS and programmed death-ligand 1 (PD-L1) expression testing were performed in the ovarian serous carcinoma. The results showed mutations of breast cancer type 1 (BRCA1) and type 2 (BRCA2), tumor protein p53 (TP53) (c.524G>A at pR175H), and heat shock protein 90 alpha family class B member 1 (HSP90AB1) (p.R456C), as well as low RNA expression score of PD-L1. Conclusion: Identification of these mutations and PD-L1 abnormality at the diagnosis of ovarian carcinoma may shed light for clinicians to provide targeted therapy with poly (ADP-ribose) polymerase (PARP) inhibitors and immune checkpoint inhibitors for ovarian serous carcinoma. This is the first documented case of ovarian serous carcinoma to have found a HSP90AB1 (p.R456C) mutation.