Umbilicated and nonumbilicated papules were present on the presternal area of a patient with eruptive vellus hair cysts. Histopathological examination of umbilicated papules showed penetration of vellus hairs through cyst walls, surrounding granulomatous foreign body reaction, and communication to the surface of the skin with released vellus hairs present in the pore. This suggests that resolution of some of the cysts in this disorder may occur by transepithelial elimination.
(Arch Dermatol 115:338-339, 1979)
Bovenmyer DA. Eruptive Vellus Hair Cysts. Arch Dermatol. 1979;115(3):338-339. doi:10.1001/archderm.1979.04010030046018