# Pigmented Birthmarks and Spinal Neurofibromas in KRAS Mosaicism—Not to Be Confused With NF1

## TL;DR

A child with skin birthmarks and spinal tumors was found to have KRAS mosaicism, a condition that can resemble neurofibromatosis.

## Contribution

This case expands the clinical spectrum of KRAS mosaicism and emphasizes its distinction from NF1.

## Key findings

- Pigmented skin lesions and spinal neurofibromas can occur in KRAS mosaicism.
- KRAS variants can cause congenital skin lesions and spinal nerve root hypertrophy.
- KRAS mosaicism should be considered in the differential diagnosis of neurofibromatosis-like presentations.

## Abstract

We report a child presenting with pigmentary skin lesions and spinal neurofibromas who was diagnosed molecularly with KRAS mosaicism. We review the previous literature of two cases of congenital skin lesions and neurofibromas and spinal nerve root hypertrophy caused by KRAS variants and highlight this presentation as an important differential diagnosis for neurofibromatosis.