Milia are small, white cysts that commonly appear on the skin. Often described as looking like tiny whiteheads, they are technically not related to acne. Instead, these bumps are caused by keratin, a protein, becoming trapped beneath the surface of the skin. Milia are very common and can occur in people of all ages, from newborns to adults. They are generally harmless and often disappear on their own, but understanding what they are and the different types can be helpful.
Milia are categorized primarily by when they appear and what triggers their development. These categories further break down into primary and secondary classifications.
Primary Milia: Keratin Cysts Formed Directly
Primary milia develop spontaneously when keratin becomes trapped and forms cysts. They are frequently observed on the face, particularly around the eyes, nose, and cheeks, in both infants and adults.
Neonatal Milia: Common in Newborns
Neonatal milia is a type of primary milia that is extremely common in newborns. It is estimated that milia are present in approximately 40% of newborn babies. These tiny cysts are typically found on the face, scalp, and upper torso of infants. Neonatal milia is a temporary condition, and these cysts usually resolve on their own within a few weeks without any intervention.
Primary Milia in Older Children and Adults
While often associated with babies, primary milia can also occur in older children and adults. In these age groups, primary milia are commonly found around the eyelids, forehead, and genitalia. Similar to neonatal milia, these cysts are also benign and may disappear within a few weeks or sometimes persist for several months.
Secondary Milia: Developing After Skin Trauma
Secondary milia are similar in appearance to primary milia but arise due to different circumstances. They develop as a consequence of blocked ducts leading to the skin’s surface. This blockage is often triggered by some form of trauma to the skin, such as injuries, burns, blisters, or certain skin conditions.
Traumatic Milia: A Result of Skin Injury
Traumatic milia fall under the category of secondary milia and are directly linked to skin injuries. These injuries can range from severe burns and rashes to more minor skin trauma. In these cases, milia appear at the site of the injury. Sometimes, traumatic milia can become irritated, leading to redness around the edges of the cyst and a noticeable white center.
Milia Associated with Drugs or Products: Reactions to External Substances
Certain medications and topical products can also contribute to the development of milia. Although rare, the use of steroid creams has been reported to induce milia in the areas where the cream is applied.
Furthermore, some ingredients commonly found in skincare and makeup products can be comedogenic for certain individuals, leading to milia formation. If you are prone to milia, it may be beneficial to avoid products containing the following ingredients, which are all types of mineral oil:
- liquid paraffin
- liquid petroleum
- paraffin oil
- paraffinum liquidum
- petrolatum liquid
- petroleum oil
Lanolin is another ingredient that has been suggested to potentially increase the likelihood of milia formation in susceptible individuals.
Other Less Common Types of Milia
Beyond primary and secondary classifications, there are other less common types of milia that are worth noting:
Juvenile Milia: Linked to Rare Genetic Disorders
Juvenile milia are associated with rare genetic disorders that affect the skin. These genetic conditions can predispose individuals to developing milia from a young age.
Milia en Plaque: Associated with Skin Disorders
Milia en plaque is a less common but distinctive form of milia. This condition is often linked to underlying genetic or autoimmune skin disorders such as discoid lupus erythematosus or lichen planus. Milia en plaque is characterized by clusters of milia on an inflamed plaque, typically affecting areas like the eyelids, ears, cheeks, or jaw. The individual cysts can be quite large, reaching several centimeters in diameter. While it is predominantly observed in middle-aged women, it can occur in adults and children of any age and gender.
Multiple Eruptive Milia: Itchy and Appearing in Crops
Multiple eruptive milia is a rare type characterized by the sudden appearance of numerous milia cysts, often accompanied by itching. These clusters of cysts can appear on the face, upper arms, and torso. The development of multiple eruptive milia can occur over a period ranging from a few weeks to several months.
Understanding the different types of milia can help in recognizing and managing them. While generally harmless and often self-resolving, if you have concerns about milia or are unsure about the type you may have, consulting a dermatologist is always a good step for proper diagnosis and advice.
