Angiosarcoma Arising in 1 of 2 Adolescent Twins With Cryptogenic Cirrhosis and MAF Gene Mutation

Primary hepatic angiosarcoma (HAS) is an exceedingly rare tumor that is often idiopathic and usually fatal. It typically occurs in a bimodal age distribution, in older adults or very young children. We describe a unique case of HAS arising at an unusual age, in an adolescent who was one of a pair of identical twins affected by cryptogenic cirrhosis and who were found to have germline loss-of-function variant in MAF, a gene that has recently been shown through animal models to be crucial in the specification of liver sinusoidal endothelial cells (LSECs). The case is the first known report of liver disease in the setting of germline MAF variants. It implicates LSEC dysfunction in both non-neoplastic and neoplastic liver disease and lends insight into the importance of LSECs in liver health and homeostasis.