Linear epidermal naevus associated with a novel mosaic heterozygous PTPN11 variant.

Jiang, Xingyuan; Chen, Tiffany X; Hu, Ronghua; Mortlock, Ryland D; Ko, Christine; Choate, Keith A · Br J Dermatol · 2025

case_report · Level V

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Abstract

We report the first case of linear epidermal naevus (LEN) associated with a novel mosaic heterozygous <i>PTPN11</i> variant (c.C1361 T, p.P454L). Genetic and histopathological analysis revealed increased RAS/mitogen-activated protein kinase pathway activation in affected skin, suggesting a distinct molecular mechanism linking <i>PTPN11</i> mosaicism to LEN. Our findings expand the genetic spectrum of LEN and provide insights into the role of <i>PTPN11</i> in cutaneous mosaic disorders.