ERBB2 and isolated hemihyperplasia: Other alterations, such as FGFR2 rearrangements or mutations (10-15%), B-Raf proto-oncogene (BRAF) V600 mutations (3%), Human Epidermal growth factor Receptor 2 (HER2) amplifications or mutations (15%) and IDH1 mutations (13%), are more prevalent, especially in patients with IH-CCA [22].