Understanding everything about milia.

The milia, also called "milia" in English, are small white subcutaneous microcysts, generally 1 to 3 mm in diameter, formed by an accumulation of dead cells and cellular debris such as keratin.

They are not painful and are benign. Milia can appear as isolated lesions or in clusters of around fifty small lesions. These present visually as small white bumps on the skin, often firm to the touch. They are sometimes described as small fat balls on the face, although their contents are not made of lipids, but mainly of keratin.

Located in several areas of the face, milia can be found around the eyes, on the nose, forehead, or chin. It is particularly common to observe a milium cyst under the eye, an area where the skin is thin and where microcysts appear more easily. They can also sometimes be seen on the ears, eyelids, or cheeks. All age groups may develop them, although infants remain the most affected.

Good to know : Milia differ from whiteheads in terms of their content: unlike whiteheads, milia do not contain sebum or bacteria.

Milia are classified into two main categories:

• Primary milia : These cysts appear spontaneously. They may be congenital (occurring in 40 to 50% of newborns), affecting the face and scalp, and resolving within a few weeks to a few months. Primary milia in children and adults, on the other hand, are more often found on the cheeks, eyelids, and forehead. Finally, cases of milia en plaque have been reported, a rare condition characterized by erythematous plaques containing numerous milia on the head and neck.

• Secondary milia : These cysts develop following various processes and appear over time. This is a localized form that may be associated with a disease, a medication, or a trauma, such as a skin abrasion or a second-degree burn . In very rare cases, secondary milia may be linked to diseases such as contact dermatitis, Sweet’s syndrome, or phototoxic reactions.

Milia appear when keratin, a protein that naturally occurs in the skin, becomes trapped beneath the epidermis. Normally, dead cells produced by skin renewal are gradually shed at the surface of the skin. But when this process is disrupted, they can accumulate in a small superficial cyst, forming those small white bumps often seen on the face. Several factors may explain this phenomenon, depending on whether the milia are primary or secondary. Blockage of hair follicles can, in particular, be promoted by the use of rich, greasy products, or have a genetic origin, as research has identified cases of milia associated with skin disorders such as genodermatoses.

As for secondary milia, several factors may be involved:

• Skin trauma : Milia can appear after an insult to the skin, such as a burn, an abrasion, or repeated friction, for example following intensive use of brushes or exfoliating tools. These microtraumas disrupt the healing process: fragments of epithelium can then remain trapped in the skin, promoting the formation of microcysts.

• Exposure to UV rays : Excessive exposure to the sun can also disrupt cellular renewal and the structure of the skin. UV radiation thickens the stratum corneum and interferes with natural desquamation, which can promote the appearance of white bumps on the face.

• Extended application of topical corticosteroids : Prolonged use of creams containing corticosteroids can weaken the skin. These molecules can lead to alterations in collagen and elastic fibers surrounding the hair follicles, which could promote the formation of milia. However, scientific data supporting this association remain limited.

• Dermatological diseases : Certain skin diseases can also be associated with the appearance of milia. This is particularly the case with epidermolysis bullosa, a disease characterized by extreme skin fragility and abnormal wound healing. During the skin repair process, small keratin-filled microcysts can form, leading to the development of secondary milia.

Although they do not pose any danger, milia can be considered unsightly by some people.

In general, milia disappear on their own within a few weeks to a few months. However, they may persist longer in the case of secondary milia. Several treatment options are then available to help them disappear more quickly.

Mechanical extraction of milia cysts.

The extraction of a milium cyst must be performed by a healthcare professional, usually a dermatologist or a medically trained aesthetic practitioner familiar with this procedure. After disinfecting the skin, the specialist makes a very superficial micro-incision using a sterile needle or a lancet to open the microcyst. The keratinous content is then gently expelled with a comedone extractor, a small dermatologic curette, or a cotton swab. This technique is quick and generally only mildly painful when the lesion is superficial.

Topical application of retinoids.

Topical retinoids , such as tretinoin or adapalene, may be prescribed in certain situations, particularly in cases of multiple milia or plaque-like milia. These vitamin A–derived molecules stimulate cell turnover and promote shedding of the stratum corneum. By accelerating the removal of dead cells, they can gradually clear the keratin plug and allow the microcyst to disappear.

Cryotherapy.

Cryotherapy involves applying liquid nitrogen at very low temperature to the lesion. The intense cold induces controlled destruction of the superficial skin cells. Dermatologists generally use a cotton swab or a cryogenic spray to target the milium precisely. After treatment, the area may become slightly red or form a small scab before the skin regenerates.

CO₂ laser ablation.

The CO₂ laser is sometimes used when milia are numerous or resistant to other methods. This laser emits light that is absorbed by the water contained in skin cells, which makes it possible to very precisely vaporize the superficial layer of the epidermis where the microcyst is located. The heat produced also stimulates collagen production, which promotes skin regeneration after the procedure.

Electrodesiccation.

The technique of electrodessication is based on the use of a fine conductive needle connected to a low-intensity electric current. When this needle is applied to the keratinized center of the milium, the heat generated causes coagulation and destruction of the microcyst. The lesion then dries out and falls off within a few days.

Antibiotics.

In certain specific cases, particularly when milia are associated with skin inflammation or an underlying dermatological condition, drug treatment may be considered. Antibiotics such as minocycline have sometimes been used. However, their use is now limited: since June 2012, medications containing minocycline have been discouraged for the treatment of acne because of the risk of allergic skin reactions. Any prescription should therefore be discussed with a physician.

Remember that these techniques must be performed by professionals. Piercing a milium cyst yourself can lead to scarring and infections caused by bacteria, fungi, or viruses, especially when hygiene and sterilization standards are not followed.

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