Malignant hepatic vascular neoplasm with novel RAF1 and GNA11 mutations: Risk stratification considerations for hepatic small vessel neoplasm (HSVN)

Abstract

GNAQ, GNA11, and GNA14 are paralogues in the GNAQ family that are mutually exclusively mutated in a group of vascular neoplasms with thin-walled capillary-like vasoformative growth, which occur at multiple sites. The primary liver tumor in this category is termed hepatic small vessel neoplasm (HSVN), which is a rare infiltrative vascular neoplasm that can be misdiagnosed as hepatic angiosarcoma and which has been described as having likely very low malignant potential. In this study, we report on a novel primary malignant hepatic vascular neoplasm with infiltrative low grade regions morphologically resembling HSVN, as well as regions suggestive of high grade transformation. Next generation sequencing demonstrated a GNA11 p.Gln209Leu mutation (in high grade regions) and a RAF1 p.Met469Ile mutation (in low grade and high grade regions). On radiographic and gross examination, the tumor was unencapsulated, poorly circumscribed, and multifocal throughout the liver. Splenic metastases were identified and were histologically similar to high grade liver tumor regions, and shared the same RAF1 mutation. These findings argue that high grade morphology and/or additional oncogenic mutations in hepatic vascular neoplasms with GNAQ family mutations heighten concern for malignant potential and we advise next generation sequencing of HSVN for risk stratification.

Keywords

• Hepatic vascular neoplasm
• Hepatic small vessel neoplasm
• HSVN
• Angiosarcoma
• GNA11
• RAF1