Mila are minute papules seen just under the surface of the skin composed of hard, whitish, keratinous material. They are in fact a cyst lined by epithelium with deposited keratin in the centre of the cyst coming from the sebaceous gland associated with a vellus hair follicle. If secondary to trauma they have also been seen associated with the eccrine (sweat) gland. When they occur in babies or young children they are often referred to colloquially as milk spots by the general population. They are harmless, but in adults, can cause cosmetic concern.
Milia should not be confused with colloid milium which presents as yellowish papules and is due to the deposition of colloid globules in the papillary dermis and is thought to be due to actinic (sun) damage.
Childhood granulomatous perioroficial dermatitis which is seen almost exclusively in Afro-Carribean children, so is also known as Facial Afro-Caribbean childhood eruption, and presents with skin coloured papules around either the eyes or mouth or both, and so can look a little similar to milia. Usually the number of papules is much more extensive and confluent than milia.
What causes Milia?
Neonatal milia are very common affecting 40 to 50% of babies and is due to blocked (occluded) vellus hair follicles which resolve spontaneously. If neonatal milia occur they are often present at birth.
Milia may be primary or secondary. When they are secondary they occur due to some form of deeper injury to the skin and the most common causes are blistering rashes such as pemphigus vulgaris or bullous pemphigoid, burns or radiotherapy. The cause of primary milia is not known but there may be a genetic predisposition and actinic (sun) damage and the use of occlusive moisturisers has been implicated.
The cysts may appear differently depending on the type of milia and age of the person. Neonatal milia, which affects 40-50% of babies usually appears on the nose, face and scalp but can also appear in the mouth.
Primary milia, in older children and adults, is more likely to appear around eyelids, cheeks, forehead and genitalia.
Other forms of milia, include milia en plaque where the cysts appear within a thick layer of plaque around ears, cheeks, jaw and eyelids. This is quite rare and usually associated with discoid lupus erythematosus or lichen planus. This is most common in middle aged women.
Eruptive milia can create lesions which can be itchy and affect face, upper arms and upper trunk
Who is at risk of Milia?
Neonatal milia affects 40-50% of all babies of any ethnicity or gender.
Less often older children and more commonly adults can develop primary milia which could be caused by using occlusive moisturisers. Primary milia occur almost exclusively on the face.
Secondary milia occur in people who have experienced some form of trauma to the skin or inflammatory skin condition. The milia occurs at the site of trauma and can occur anywhere on the body.
What are the symptoms of Milia?
Images of Milia
These images are kindly provided by DermNetNZ.org for non-commercial use, for the purpose of education and information. The images have not been modified and DermNetNZ do not endorse The London Skin and Hair Clinic. You can find a copy of the license at http://creativecommons.org/licenses/by-nc-nd/3.0/nz/.
How does a dermatologist diagnose Milia?
In most cases the diagnosis would be made through physical examination by a Dermatologist. However, in older children and adults, if the underlying cause is unclear a skin biopsy may be needed to make a full diagnosis.
How does a dermatologist treat Milia?
Dermatologists tend to advise not treating milia in babies or children as they normally resolve by themselves.
First-line treatment in adults, if sought, is de-roofing of each individual milium with a hypodermic needle and expressing the minute cystic lesion, which when extracted looks like a small, hard, white pearl. This leaves a small crust or scab which sloughs off in one or two days rendering an excellent cosmetic result.
Because the lesion extracted is firm and underneath the epidermis it is not amenable to removal with a comedone extractor. To remove the lesion this way would cause too much trauma to the surrounding skin.
Fine-wire hyfrecation which involves the use of a fine tip needle which delivers either an electric current or radiofrequency is also an effective treatment. Ablative lasers such as the Erbium-Yag or CO2 laser have also been used to treat milia.