Background:
Primary pancreatic mucoepidermoid carcinoma (MEC) is an extremely rare malignant tumor with unclear etiology and pathogenesis. There are only eleven reported cases in English papers published from 1959 to 2020. MEC generally occurs in the salivary gland, but cases in the pancreas have also been reported. Although being considered as a low-grade indolent carcinoma, pancreatic MEC always invades the surrounding lymph node and metastasizes. The prognosis of pancreatic MEC is unsatisfactory. To date, the genetic alterations, mechanistic relationships among mutated genes and signaling pathways of pancreatic MEC are unclear.
Patient and methods:
This paper presents a case of rare primary pancreatic MEC in a 56-year-old male patient with liver metastasis. Radical surgery of distal pancreatectomy and radiofrequency ablation (RFA) of two liver metastatic lesions is conducted. Targeted-gene sequencing and bioinformatics analysis tools, including STRING, DAVID, cBioPortal, DGidb and Human Protein Atlas database (HPA), are used to clarify the biological functions and features of mutated genes in pancreatic MEC.
Results:
Eight gene mutations (TP53, KRAS, ATR, FLI1, FLT4, MAGI2, RBM10, and TNFAIP3) were observed, and a tumor mutation burden (TMB) of 5.6 muts/Mb was calculated in the pancreatic MEC using targeted-gene sequencing. The patient subsequently underwent adjuvant chemotherapy and died three months after surgery. Gene-gene interaction network was constructed, which showed the significant interactions among eight mutated genes. In terms of the functions and pathways of eight gene mutations based on GO and KEGG, 20 tumor-related results are presented in this paper, Furthermore, the biological functions and features of pancreatic MEC are further compared with pancreatic ductal adenocarcinoma.
Conclusion:
Pancreatic MEC requires early and effective treatment, and lymph node metastases and multiple organ metastases were unfavorable prognostic factors. Pancreatic MEC can be compared with other pancreatic cancers that have characteristic clinical phenotype, molecular alterations, functional information and enrichment pathway.