CTNNB1-mutated melanocytic lesions with DPN like features: a distinct subtype of melanocytic tumors? A report of two cases

Excerpt

CTNNB1 mutations have been reported in various types of tumors, including melanoma [1]. The CTNNB1 gene encodes for the protein β-catenin, which plays an important role in cell-cell adhesion. Furthermore, it has a signaling role in the Wnt/β-catenin pathway, where it induces gene transcription [2]. Mutations in the CTNNB1 gene can result in accumulation of β-catenin, which can cause activation or suppression of individual gene promoters. This results in upregulation of epithelio-mesenchymal transition (EMT), which seems to be associated with invasion. However, the mutation does not always occur in malignant tumors and the prognostic impact of a CTNNB1 mutation seems to depend on the type of lesion [3]. Regarding melanocytic lesions, CTNNB1 mutations have been reported in some melanomas, approximately 2–4% [4‐7]. CTNNB1 mutations are found on exon 3, and frequently (~50%), it concerns missense mutations located at c.110, which result in a substitution at serine 37, e.g., c.110C > T (p.(Ser37Phe)), which results in a more stable β-catenin protein and thus increased transcription of TCF/LEF-responsive target genes [8]. …