I just came across the diagnosis of trichostasis spinulosa, which I have seen in my practice on occasion and have failed to come up with a diagnosis.
eMedicine states, “In trichostasis spinulosa (TS), clusters of vellus hairs become embedded within hair follicles, with resultant elevated, dark, spiny papules on the face or trunk. Trichostasis spinulosa frequently is discovered as an incidental finding, and often it is confused with keratosis pilaris or acne comedones.”
This condition is more common in men, but does not cause risk for the people having it, just some cosmetic deformities of varying degrees. To see the various forms that it takes, see Google Image Search. Maybe you have seen these on your own body and wondered about it.