Eruptive vellus hair cyst
Eruptive vellus hair cysts (or EVHC) are small lesions that occur most often in the chest wall, abdomen and extremities, often with a crusted surface. EVHC may occur randomly, or it can be inherited as an autosomal dominant trait; sporadic cases usually appear at 4–18 years of age.
Source: Wikipedia — Eruptive vellus hair cyst (CC BY-SA 4.0)