Abstract
Background Primary hepatic mucoepidermoid carcinoma (HMEC)is extremely rare and the molecular etiology is still unknown.Recently, The CRTC1-MAML2 fusion gene was detected in a primary HMEC which is often associated with MEC of salivary gland in the literature. Methods a 64-year-old male was diagnosed with HMEC based on malignant squamous cells and mucus-secreting cells in immunohistochemical examination. Whole-exome sequencing(WES) and sanger sequencing were used to reveal the molecular characteristics of HMEC,and analysis with public datas among hepatocellular carcinoma, cholangiocarcinoma and salivary MEC. Meanwhile, The susceptibility genes were identified in pedigree investigation.Result Significant somatic mutations in GNAS,KMT2C,ELF3 genes were identified in primary HMEC by WES and sanger sequencing. Meanwhile, through public data analysis, somtatic GNAS gene alterd in 2.1% hepatobiliary tumors, and typically GNAS occur at exon 8, in which Arg201 is converted to either a cysteine (R201C) or a histidine (R201H) related with cholangiocarcinoma associated with parasite infection .Furthermore, heterozygous germline mutations of FANCA, FANCI, FANCJ/BRIP1 and FAN1 genes were also identified. Pedigree investigation verified that mutation of susceptibility genes of Fanconi's anemia were present in the pedigree.Conclusions It was the first time to demonstrate the molecular etiology of the rare HMEC associated with germline Fanconi’s anemia mutations and somatic GNAS R201H mutation.