That's a very odd skin condition - its not something that can be diagnosed from a photo. A complete medical history would be helpful and maybe even a biopsy would be needed. My first thought is that they could be some type of response to repeated exposure to an industrial irritant such as fiberglass, sand, silica, or metal shavings. But it could also be something like an epidermoid cyst, granuloma, or something more serious such as a symptom of sarcoidosis. Since there is a wide range of possibilities, it seems like seeing a doctor sooner than later would be a good idea.