Overview
Milia are common non-cancerous (benign) skin findings in people of all ages. Milia formed directly from sloughed-off skin, known as primary milia, are small, fluid-filled cysts usually found on the faces of infants and adults, while lesions formed indirectly, known as secondary milia, are small cysts found within areas of skin affected by another skin condition.
Milia are formed when skin does not slough off normally but instead remains trapped in pockets on the surface of the skin. An individual milium is formed from a hair follicle (pilosebaceous unit) or from a sweat gland (eccrine gland). In primary milia in infants, the oil gland (sebaceous gland) may not be fully developed. Secondary milia often develop after injury or blistering of the skin, which disrupts and clogs the tubes (glandular ducts) leading to the skin surface.
