- One- to three-millimeter pigmented cysts presenting most commonly on the chest, abdomen or extremities
- Single, sporadic lesions usually present in the first two decades of life.
- Multiple lesions represent an autosomal dominant disorder known as eruptive vellus hair cysts. These present at a younger age and can be associated with other cutaneous lesions (steatocystoma multiplex, trichostasis spinulosa, pachyonychia congenita) and neurologic disorders.
- Dermal cyst lined by squamous epithelium with an attenuated granular layer
- The cyst contains vellus hair shafts and lamellated keratin
- The cyst wall sometimes contains telogen-like hair follicles.