Simultaneous p53 and KRAS mutation in a high-grade serous carcinoma with deceptive appearance of a low-grade carcinoma. A case report

• Published in: Gynecologic oncology reports Vol. 47; p. 101197
• Main Authors: Marketkar, Shivali, Sung, C. James, Quddus, M. Ruhul
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.06.2023; Elsevier
• Subjects: Case Report; K-RAS mutation; Low- and high-grade serous carcinoma; P53 mutation; Serous carcinoma; Serous carcinoma; Low- and high-grade serous carcinoma; K-RAS mutation; P53 mutation
• ISSN: 2352-5789; 2352-5789
• DOI: 10.1016/j.gore.2023.101197

•High grade serous carcinoma’s have typical histological features with mutated p53 staining.•Distinction between high grade and low grade serous carcinomas are mostly straightforward.•Our case illustrates unique tumor with morphological pattern of a low grade carcinoma with simultaneous p53 mutation.•The tumor is a high grade serous carcinoma with K-RAS mutation, highly unusual as documented by Cancer Genomic Atlas. Low-grade and high-grade serous carcinomas have unique clinical, morphological, underlying molecular alterations, and vastly different biologic behavior (Prat et al., 2018, Vang et al., 2009). The differentiation into high and low-grade serous carcinoma is important for clinical management and prognosis and is easily recognized by practicing pathologists. High-grade serous carcinoma is characterized by marked nuclear atypia and pleomorphism, frequent, often atypical mitosis with papillary or three-dimensional clusters, p53 mutation, and block-like p16 staining. In contrast, low-grade serous carcinomas have a different morphologic appearance with micropapillary formation, small nests of tumor cells having low to intermediate grade nuclei, and absence of significant mitosis. Low-grade serous carcinoma is often associated with micropapillary variant of ovarian serous borderline tumor. The low-grade serous carcinoma shows wild type p53 expression, patchy p16 staining, and often K-RAS, N-RAS, and/or B-RAF mutation. Here we report a case of mullerian high grade serous with a deceptive morphology resembling low-grade serous carcinoma with micropapillary features and moderate nuclear atypia. However, the tumor is simultaneously p53 and K-RAS mutated. This case illustrates three critical issues; a) potential to be mistaken as a low-grade serous carcinoma because of morphologic appearance and relative uniform cytologic feature. b). raise the question of true progression of low-grade to high-grade serous carcinoma, a rare phenomenon as described in the literature, and c). whether the biologic behavior and/or response to therapy would differ from the classic forms.