Whole-exome sequencing reveals the etiology of the rare primary hepatic mucoepidermoid carcinoma

Background Primary hepatic mucoepidermoid carcinoma (HMEC) is extremely rare and the molecular etiology is still unknown. The CRTC1-MAML2 fusion gene was previously 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. Fluorescence in situ hybridization (FISH) was used to detect the CRTC1-MAML2 fusion gene in HMEC. Whole-exome sequencing and Sanger sequencing were used to reveal the molecular characteristics of HMEC and analysis was performed with public data. Pedigree investigation was performed to identify susceptibility genes. Results Hematoxylin–eosin staining and immunohistochemistry revealed that the tumor cells were composed of malignant epidermoid malignant cells and mucous cells, indicating a diagnosis of HMEC. The CRTC1-MAML2 fusion gene was not detected in the primary HMEC, and somatic mutations in GNAS, KMT2C and ELF3 genes were identified by sequencing. Analyses of public data revealed somatic GNAS alterations in 2.1% hepatobiliary tumors and relation with parasite infection. Heterozygous germline mutations of FANCA, FANCI, FANCJ/BRIP1 and FAN1 genes were also identified. Pedigree investigation verified that mutation of Fanconi’s anemia susceptibility genes were present in the pedigree. Conclusions Here we provide the first evidence of the molecular etiology of a rare HMEC associated with germline Fanconi’s anemia gene mutations and somatic GNAS R201H mutation.

Whole-exome Sequencing Reveals the Etiology of the Rare Primary Hepatic Mucoepidermoid Carcinoma

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.