Dermatology MCQ - Infiltrative and Neoplastic Disorders - Milia

A newborn is brought for their first well-baby visit. The parents are concerned about tiny, white bumps scattered across the infant's nose, cheeks, and chin. On examination, you note multiple, 1-2 mm, firm, white, dome-shaped papules. They are not surrounded by erythema and are non-tender. Which of the following is the most accurate statement regarding the pathogenesis and management of these lesions?

A. They are caused by maternal androgens stimulating neonatal sebaceous glands and will resolve with gentle cleansing.
B. They are small epidermoid cysts derived from the pilosebaceous unit and will typically resolve spontaneously within weeks.
C. They are keratin-filled cysts arising from the infundibulum of vellus hair follicles and will typically resolve spontaneously within weeks.
D. They are collections of superficial yeast and require treatment with a topical antifungal agent.
E. They are a form of neonatal acne triggered by skin flora and should be treated with topical benzoyl peroxide.

Correct Answer: C. They are keratin-filled cysts arising from the infundibulum of vellus hair follicles and will typically resolve spontaneously within weeks.

Answer and Explanation

The correct answer is C. This question describes the classic presentation of neonatal milia. The key clinical clues are the appearance in a newborn, the location on the face, and the description of multiple, tiny, firm, white papules. Milia are tiny, superficial, keratin-filled cysts. In neonates, they are thought to arise from the pilosebaceous unit, specifically the infundibulum of vellus hair follicles. They are benign and almost always resolve spontaneously as the skin matures and the keratin is shed.

Why the Other Options are Incorrect:

• A. They are caused by maternal androgens stimulating neonatal sebaceous glands...: This describes neonatal cephalic pustulosis (often mistakenly called "baby acne"), which presents as inflammatory erythematous papules and pustules, not non-inflammatory white cysts.

• B. They are small epidermoid cysts derived from the pilosebaceous unit...: This is subtly incorrect. While milia are a type of epidermoid cyst histologically, they are distinct from the larger, common epidermoid cysts seen in adults. The term "milia" is reserved for these specific, superficial, small cysts. Stating they are derived from the vellus hair follicle infundibulum is more precise.

• D. They are collections of superficial yeast...: This is incorrect. While Malassezia yeast may play a role in neonatal cephalic pustulosis, milia are purely keratinous cysts with no infectious component.

• E. They are a form of neonatal acne...: This is incorrect. As stated, neonatal acne (cephalic pustulosis) is inflammatory. Milia are non-inflammatory retention cysts. Applying benzoyl peroxide to an infant's delicate skin for milia would be inappropriate and potentially irritating.

Additional High-Yield Information for Exams:

• Histopathology: Milia are characterized by a small, cystic structure located in the superficial dermis, just beneath the epidermis. The cyst wall is lined by stratified squamous epithelium, and the lumen is filled with laminated keratin. This is identical to the lining of an epidermoid cyst, just on a much smaller scale.

• Types of Milia:

  • Primary Milia: Arise spontaneously, often on the faces of infants and adults. In adults, they are common on the eyelids and cheeks.

  • Secondary Milia: Arise in areas of skin trauma, blistering, or following inflammatory processes (e.g., after burns, dermabrasion, or in patients with epidermolysis bullosa). These result from damage to the eccrine sweat ducts or the epidermis, leading to entrapped keratin.

• Differential Diagnosis: The main differential in a newborn includes:

  • Milia: As described.

  • Neonatal Cephalic Pustulosis: Inflammatory red papules and pustules.

  • Sebaceous Hyperplasia: Yellowish, grouped papules on the nose, also common and self-resolving in newborns.

• Prognosis: Excellent. Neonatal milia typically resolve spontaneously within the first few weeks to months of life without any intervention.

• Management & Rationale:

  • Rationale: The primary goal is parental reassurance and prevention of skin damage from unnecessary treatments.

  • First-line: Reassurance and observation. No treatment is necessary for neonatal or most primary milia.

  • Treatment (if desired for cosmetic reasons in older children or adults): The cysts are very superficial. Treatment involves gentle incision and expression of the tiny keratin pearl using a sterile needle or blade. Other options include light cautery or laser ablation. Topical retinoids can be used to help hasten resolution by increasing skin cell turnover.