Conditions like genetic or autoimmune skin, keratin trapped beneath the skin and injury cause milk spots. Healthline explains that milk spots, also known as milia, usually accompany some type of skin damage including blistering injuries like poison ivy; burns; long-term sun damage; long-term use of steroid creams; skin-surfacing procedures, like dermabrasion or laser resurfacing; and skin conditions, like bullous pemphigoid, epidermolysis bullosa and porphyria cutanea that cause blistering.
Milk spots occur in different kinds of milium cysts. Healthline explains that the condition most often occurs in newborns with spots around the face, eyelids, cheeks, scalp and upper torso, but the condition usually disappears within a few weeks. Juvenile milia develops from genetic disorders like basal cell nevus syndrome, pachyonychia congenita, Gardner syndrome or Bazex-Dupré-Christol syndrome. Traumatic milia arise from injury and may cause irritation. Milia en plaque associated with autoimmune skin or genetic disorders occurs on the eyelids, ears, cheeks, and jaw. The primary milia in children and adults that occurs from keratin trapped beneath the skin affects the eyelids, forehead and genitalia and may only last for a few weeks or stick around for several months. Multiple eruptive milia itches and occurs on the face, upper arms and torso.