Ovarian low grade serous carcinoma: A case report

Abstract

<h3>Case report</h3> We present a case of a 76-year-old woman with bilateral ovarian masses and a right upper quadrant cyst detected on imaging. Histology of the solid tumour component in both ovaries showed a low grade serous carcinoma with sheets and irregular nests of cells with uniform round to oval nuclei and evenly distributed chromatin. The solid component merged with a cystic component, showing variable features of serous cystadenoma and borderline serous change. The cells showed positive staining for WT-1, and were negative for p53. The right upper quadrant cyst showed similar features. <h3>Discussion</h3> Low grade and high grade ovarian serous carcinomas are two distinct tumour types with different underlying pathogenesis, molecular events, and prognosis. Low grade serous carcinomas are hypothesised to evolve from adenofibromas or borderline tumours, and have frequent mutations of the KRAS, BRAF, or ERBB2 genes, and lack TP53 mutations. This is termed the Type I pathway. The progression to invasive carcinoma is a slow step-wise process. Low-grade tumours are indolent and have better outcome than high-grade tumours. In contrast, high grade serous carcinomas arise via the Type II pathway and the vast majority are characterised by TP53 mutations and lack mutations in KRAS, BRAF, or ERBB2. Immunohistochemical stains for p53, pl6, p53 and Ki-67 for distinction of low- from high-grade tumours can be helpful in selected instances. This case is presented to show the spectrum of histological appearances in a low grade ovarian serous carcinoma, for instance areas resembling serous cystadenoma through to borderline serous change.