Milium (Plural Milia)

A milium refers to a small cyst that contains a skin protein called keratin. Usually, milium is found in clusters and together they are known as milia. These cysts are considered to be harmless and appear as pearly-white bumps just under the surface of the skin.

Milia have no prevalence in age and sex; everyone has equal chances of developing this skin condition. Usually, they arise on the face, especially on the eyelids and cheeks.

There are different types of milia, which are discussed further below.

Types of Milia

Neonatal milia affects 40 to 50% of newborn babies. The occurrence of lesions varies. They are usually found on the nose, but can be found inside the mouth on the mucosa or palate, on the face, upper trunk, or scalp. Healing typically takes a few weeks.

Primary milia in children and adults is found on the forehead, cheeks, and genitalia. In young children, milia can also arise on the nasal crease. The healing time can range from a few weeks to several months.

Juvenile milia can be either congenital (present at birth) or appear later in life. This particular type of milia is associated with Bazex-Dupre-Christol syndrome, Gardner syndrome, basal cell naevus syndrome, and other genetic disorders.

Milia en plaque is usually found behind the ear, on the cheek, jaw, or eyelid. It affects both children and adults, especially middle-aged women.

Multiple eruptive milia usually affect the face, upper trunk, and upper arms. These lesions can be either asymptomatic or itchy.

Traumatic milia usually arise from eccrine sweat ducts. They occur at the site of injury when the healing process begins. Examples of injuries include blistering rashes, dermabrasion, or thermal burns.

Drug-associated milia can be caused by hydroquinone, corticosteroids, and phenols.

Diagnosis

Milia have a defined appearance. A skin biopsy can sometimes be performed for clarification of diagnosis. Milia should not be confused with comedones, syringomas, and cysts. Colloid milia have a clinical feature of golden-coloured bumps that appear on the temples and cheeks, caused by excessive sunlight exposure.

Treatment

Milia do not require any treatment unless they appear concerning to the patient. They usually resolve on their own within a few months. However, further trauma should be minimised in order to prevent the development of new lesions in the future.

Lesions can be de-roofed via a sterile needle or blade, with all contents pricked out or expressed. These lesions can also be destroyed by cryotherapy, curettage, or diathermy. For widespread lesions, topical retinoids can be helpful. Cosmetic procedures such as chemical peels, dermabrasion, and laser ablation have shown successful results.