Primary Peritoneal Carcinoma in a BRCA1/2-negative, PALB2-positive patient

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Primary Peritoneal Carcinoma in a BRCA1/2-negative, PALB2-positive patient

Highlights

• • First reported case of PPC after BSO in a BRCA1/2-negative, PALB2-positive patient
• • The PALB2 mutation and genetic counseling is discussed
• • Multi-gene panel testing can benefit prognostic factors and targeted therapy

1. Introduction

Primary Peritoneal Carcinoma (PPC) is a cancer of the abdominal peritoneal lining without involvement of the ovaries or identifiable primary tumor. Its estimated annual incidence in the United States is 0.46 per 100,000 women(Goodman et al., 2009). The actual incidence of low-grade serous PPC is much lower (< 1/150,000) (Rothacker et al., 1995). Most cases are serous subtype with cellular origin identical to that of epithelial ovarian carcinoma. PPC often mimics ovarian and fallopian tube cancers. It accounts for roughly 10% of ovarian carcinomas that have been presumably misdiagnosed (Rothacker et al., 1995).

Women undergoing prophylactic bilateral salpingo-oophorectomy (BSO) can still develop PPC years later, suggesting that certain epithelial peritoneal cancers do not originate from the ovarian surface. Instead, ovarian epithelial tumors and PPC are hypothesized to share a common embryologic origin with similar germline and somatic mutations. In current literature, nearly all PPC cases have been reported in women with a known BRCA1/2 germline mutation. However, there have been minimal studies on genetic testing outside of BRCA1/2 mutations in patients with PPC. Here, we report a case of a BRCA1/2-negative patient who had undergone prophylactic BSO and presented years later with PPC (19 years) and was subsequently found to carry a mutation in PALB2.....