Nevus anemicus is a cutaneous finding characterized by focal pallor of skin without textural irregularity due to congenital local hypersensitivity of cutaneous blood vessels to catecholamines. The vasoconstriction and subsequent pallor of the affected skin mimics hypopigmentation, but this usually congenital change has no associated pigmentary alteration. Nevus anemicus usually involves the trunk, but lesions on the face and extremities have been observed. It is usually first noticed at birth or in early childhood, but because it can often be subtle and is asymptomatic, it is frequently an isolated incidental finding.

Nevus anemicus may also occur in association with several syndromes, including neurofibromatosis (up to 4% of cases) and phakomatosis pigmentovascularis (PPV), a syndrome consisting of combinations of cutaneous and vascular findings that may include capillary malformations, dermal melanocytosis, and nevus spilus, caused by mutations in the GNAQ / GNA11 pathways. Nevus anemicus has also been seen in patients with Legius syndrome with confirmed SPRED1 mutation and Noonan syndrome with lentigines, with a confirmed PTPN11 mutation.