# Infantile myofibromatosis and capillary malformation of the skin due to PDGFRB mosaicism

## TL;DR

A patient with skin and muscle tumors had a genetic mutation in PDGFRB, which likely caused her condition.

## Contribution

This case is the first to link PDGFRB mosaicism to both myofibromatosis and capillary malformations.

## Key findings

- A PDGFRB variant (p.N666K) was found in myofibromas and a capillary malformation but not in blood cells.
- The findings suggest PDGFRB mosaicism causes a spectrum of anomalies including myofibromas and vascular malformations.

## Abstract

This report describes the case of a 25-year-old female patient with multicentric infantile myofibromatosis since early infancy, superficial capillary malformations and congenital hypoplasia of the third and fourth finger of her right hand. All known lesions were located in the upper extremities, the chest and the upper back. A pathogenic, gain-of-function platelet-derived growth factor receptor-beta (PDGFRB) variant (p.N666K, c.1998 C > A) was detected in two myofibromas and in a capillary malformation on the upper back, but not in DNA obtained from blood mononuclear cells. Thus, PDGFRB mosaicism appears to account for the patient’s myofibromas and capillary malformations, supporting a broad spectrum of PDGFRB-driven anomalies ranging from myofibromas to vascular malformations.