Milia are very common, benign, keratin-filled epidermoid cysts that occur in individuals of all ages, from infants to elderly persons.¹

• Primary milia are typically seen in infants but may also occur in children and adults. Primary milia arise on facial skin bearing vellus hair follicles.
• Secondary milia result from damage to the pilosebaceous unit.
• Milia en plaque and multiple eruptive milia are distinct entities.

Epidemiology¹

• Milia are common in all ages and both sexes. Milia affect approximately 50% of infants.
• Multiple eruptive milia and milia en plaque are rare.

Presentation

• Milia are superficial, uniform, pearly-white to yellowish, domed lesions measuring 1-2 mm in diameter.
• Milia most often arise on the face and are particularly prominent on the eyelids and cheeks, but they may occur elsewhere.²
• They are usually asymptomatic but may be itchy.

Primary milia

• Primary milia in infants occur on the face, especially the cheeks, nose and around the eyes. They may be more widespread on the scalp, face and upper trunk.
• They may also be found on the mucosa (Epstein's pearls) and palate (Bohn's nodules).¹
• In older children and adults, they also develop on the face, particularly around the eyes.
• Primary milia in children and adults are most often on the eyelids, cheeks, forehead and genitalia. They may clear in a few weeks or persist for months or longer.
• Juvenile milia may be present at birth or appear later in life. They may be associated with Gardner's syndrome and other genetic disorders.

Milia en plaque

• The small papules arise on a distinct, erythematous plaque in the postauricular area, unilaterally or bilaterally.
• They are usually seen on the eyelids, behind the ears, on cheeks or on the jaw. Submandibular plaques and lesions on the pinna have been reported.^3,4
• They especially affect middle-aged women and may be associated with other skin disease, e.g. pseudoxanthoma elasticum, discoid lupus erythematosus, lichen planus.²

Multiple eruptive milia

Crops of milia appear over a few weeks to months.⁵ Most often, they affect the face, upper arms and upper trunk.²

Secondary milia

• These are found anywhere on the body where there has been a predisposing condition.
• Traumatic milia occur at site of injury as skin heals, e.g. following burns or blistering rashes.⁶
• Milia may rarely follow the use of topical medication, e.g. 5-fluorouracil cream, corticosteroid creams.¹

Investigations

• The clinical appearance is diagnostic in simple milia and no further investigations are required.
• In elderly people with sun-damaged skin, a biopsy is needed to exclude nodular elastosis of the skin (Favre-Racouchot syndrome). If milia en plaque are suspected, a biopsy is prudent to confirm the diagnosis.

Differential diagnosis¹

• Acne vulgaris.
• Syringoma.
• Trichoepithelioma.
• Lichen planus follicularis tumidus.
• Follicular mucinosis.

Another differential diagnosis is closed comedones which are more cream than white. They also usually have a small punctum as well as being associated with open (black) comedones.

Primary care management

• Often no treatment is required.
• Some milia may be removed with a needle, as they often shell out easily.⁷
• Topical peeling agents do not work.

Prognosis

They are harmless but unsightly. They tend to resolve within a few weeks in infants but may persist in older children and adults, requiring removal with a needle (no anaesthetic is required).¹

When to refer

For confirmation of diagnosis or reassurance. It is worth referring patients with suspected milia en plaque.

Document references

1. Cooper S; Milia, Medscape, Sep 2009
2. Milium, milia, DermNet NZ
3. Garcia Sanchez MS, Gomez Centeno P, Rosen E, et al; Milia en plaque in a bilateral submandibular distribution. Clin Exp Dermatol. 1998 Sep;23(5):227-9. [abstract]
4. Smith MA; Localized milia formation on pinna due to topical steroid application. Clin Exp Dermatol. 1977 Sep;2(3):285-6.
5. Batra P, Tsou HC, Warycha M, et al; Multiple eruptive milia. Dermatol Online J. 2009 Aug 15;15(8):20. [abstract]
6. Bryden AM, Ferguson J, Ibbotson SH; Milia complicating photocontact allergy to absorbent sunscreen chemicals. Clin Exp Dermatol. 2003 Nov;28(6):668-9.
7. Thami GP, Kaur S, Kanwar AJ; Surgical Pearl: Enucleation of milia with a disposable hypodermic needle. J Am Acad Dermatol. 2002 Oct;47(4):602-3.

Internet and further reading

• Berk DR, Bayliss SJ; Milia: a review and classification. J Am Acad Dermatol. 2008 Dec;59(6):1050-63. Epub 2008 Sep 25. [abstract]