Eruptive vellus hair cysts--a facial variant

A 29-year-old man and a 29-year-old woman developed over fifty asymptomatic, slate-colored macules disseminated mainly on the forehead. Histologic study revealed keratinous cysts in the dermis, lined by a few layers of epithelial cells with rudimentary hair bulb-like structures. The cysts' contents were vellus hair fragments and laminated horny material. Ultrastructural studies of the second case disclosed that the keratinization of the cyst wall was similar to that of the infundibular portion of the outer root sheath. It is suggested that our two cases are a type of follicular hamartoma. Similar follicular hamartomas, eruptive vellus hair cysts have been reported previously. The cysts were located in the chest and/or extremities and had a tendency to be eliminated transepidermally. Although these clinical features were different from ours, the characteristic histologic features were the same; therefore, our cases might be a variant of eruptive vellus hair cysts.