Hair follicle nevus, previously known as congenital vellus hamartoma, is an uncommon and benign hamartoma that is evident at birth or observed in early infancy. It is characterized by a discrete skin-colored papule or nodule that is often pedunculated. The lesion typically presents on the face, often in the distribution of the first brachial arch. Rare extracephalic locations of hair follicle nevi have been reported in the literature, including the neck and abdomen. Hair follicle nevus usually appears as a solitary lesion; however, multiple lesions have been described.

It is hypothesized that the lesions occur as a result of somatic point mutations. While hair follicle nevi are commonly congenital, they can be less frequently acquired, presenting in adults. Isolated reports note possible links to epidermal nevus-like lesions and frontonasal dysplasia. Moreover, a single case of hair follicle nevus has been described in association with ipsilateral leptomeningeal angiomatosis of the brain and congenital alopecia.

Given the rarity of this skin condition, its distribution and prevalence among different races and ethnicities is unknown.