From NFlection Looks to Erase NF1 Tumors With Drug That Only Goes Skin Deep:

Neurofibromatosis (NF) is conditions in which tumors grow, symptoms include light brown spots on the skin.
Neurofibromatosis (NF) is conditions in which tumors grow, symptoms include light brown spots on the skin.

Image: iStock/Sinhyu
https://www.istockphoto.com/portfolio/gi15606757?assettype=image&mediatype=photography&sort=best