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Histopathology. 2019 May 20. doi: 10.1111/his.13924. [Epub ahead of print]

Correlation of molecular and morphologic features of appendiceal epithelial neoplasms.

Author information

1
Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan.
2
Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan.
3
Graduate Institute of Pathology, College of Medicine, National Taiwan University, Taiwan.

Abstract

AIMS:

The aims of this study were to identify the genetic features of appendiceal epithelial neoplasm and correlate the genetic features and morphology.

METHODS AND RESULTS:

We analyzed the genetic features of a series of 47 appendiceal epithelial neoplasms of various morphologies by using targeted next-generation sequencing of 11 genes commonly mutated in gastrointestinal neoplasms. Seven of nine serrated polyps harbored BRAF mutations, which are rare in other types of tumors. Most cases of low-grade appendiceal mucinous neoplasms (LAMNs) exhibited GNAS and KRAS mutations. LAMNs with a coexisting serrated polyp were all KRAS mutated. Four LAMNs with mutations in the Wnt/β-catenin pathway, either through inactivating mutations in APC or RNF43 or through activating mutations in CTNNB1, had focal proliferation of mucin-poor low-grade tumor cells, reminiscent of colorectal adenomas. Mutations in the Wnt/β-catenin pathway were also identified in high-grade appendiceal mucinous neoplasms, suggesting that Wnt/β-catenin pathway activation is the driving force for the progression of a LAMN to a higher grade lesion. Adenomatous polyps frequently had APC, KRAS, and TP53 mutations and were morphologically and molecularly similar to adenomatous polyps of the colorectum.

CONCLUSIONS:

Our results indicate a close association between morphology and genetic events in appendiceal neoplasms and suggest a phylogenetic relationship between different entities. This article is protected by copyright. All rights reserved.

PMID:
31111538
DOI:
10.1111/his.13924

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