Spitz-Type Proliferative Nodule With Novel LMNA-RAF1 Fusion Arising Within a Large Congenital Melanocytic Nevus

Document Type

Conference Proceeding

Publication Date

7-1-2024

Publication Title

Am J Dermatopathol

Abstract

Congenital melanocytic nevi (CMN) are benign melanocytic neoplasms caused most often by post-zygotic mosaic mutations in NRAS or BRAF.1 Proliferative nodules (PN) may arise within CMNs and show similar rates of NRAS and BRAF mutations, supporting their evolution from a common precursor. Recently, 3 reports have implicated fusion transcripts in RAF1 as the driver of CMNs.2-4 Clonality was confirmed in 2 via sampling of multiple nevi and mosaicism was confirmed in one through absence of the fusion in blood. Preservation of the kinase domain was observed in all 3, suggesting a similar mechanism of MEK activation as its BRAF isoform.5 We previously published on an interesting PN in a ten-year-old boy resembling an angiomatoid spitz tumor; 5 years later, the patient presented with additional PNs with angiomatoid spitz morphology, and sequencing revealed an LMNA-RAF1 fusion. We thus present the fourth case of a RAF1 fusiondriven proliferation in the context of a CMN, further adding to the wide range of its fusion partners and making it worthy of future investigation.

Volume

46

Issue

7

First Page

S30

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