Myxoid hepatocellular adenoma, a rare variant of hepatocellular adenoma with distinct imaging features: A case report with immunohistochemical and molecular analysis and literature review.

Summary Preoperative imaging and histopathology, immunohistochemistry and molecular analysis after resection of 2 hepatocellular adenomas (HCAs) (20 and 2 cm) in a 53-year-old female patient were performed. On imaging, the large lesion resembled a myxoid HCA, while the small lesion resembled a more conventional HCA with a small myxoid/fluid area. On microscopy, the large lesion showed cords and nests of hepatocytes embedded in abundant myxoid matrix, while the small lesion resembled a conventional HCA with small foci of myxoid change and serosities; both consistent with a myxoid HCA. Immunophenotyping and molecular subtyping excluded inflammatory HCA, CTNNB1 mutated HCA and sonic hedgehog HCA, and was consistent with HNF1A mutated HCA. The myxoid change as well as the serosities may allow imaging diagnosis of myxoid HCA. As fluid vacuoles can also be present in ASS1 + HCA, sonic hedgehog HCA has to be considered in the differential diagnosis.