Aesthetic Dermatology MCQ - Peeling related Milia and Acneform Eruption

A 22-year-old woman with Fitzpatrick skin type II undergoes a series of superficial salicylic acid peels for comedonal acne. Six weeks after her third peel, she develops multiple, firm, white, 1-2 mm papules on her cheeks and chin. The lesions are asymptomatic and do not resemble her previous acne. Which of the following is the most likely diagnosis and the underlying mechanism?

A) Milia; occlusion of pilosebaceous units due to enhanced keratinization
B) Acneiform eruption; irritation folliculitis from post-peel products
C) Closed comedones; retention of keratin and sebum
D) Allergic contact dermatitis; hypersensitivity to post-peel ingredients
E) Viral molluscum; contact transmission from contaminated equipment

Correct Answer: A) Milia; occlusion of pilosebaceous units due to enhanced keratinization

Explanation

This presentation is classic for milia, a common benign complication following chemical peels and other skin resurfacing procedures.

Key Features of Milia:

• Appearance: Small (1-2 mm), firm, white, dome-shaped papules that are asymptomatic.

• Location: Common on the cheeks, eyelids, and chin.

• Timing: Typically appear weeks to months after a procedure as the skin heals.

• Pathophysiology: Milia are tiny epidermal inclusion cysts filled with keratin. They form due to:

  • Occlusion of pilosebaceous units: The healing process after a peel can lead to enhanced keratinization and temporary disruption of normal epidermal shedding, trapping keratin within the skin.

  • Use of occlusive ointments: Post-peel emollients (e.g., petrolatum) can contribute to pore occlusion.

Why Not the Other Options?

• (B) Acneiform eruption: Would present with inflammatory papules and pustules, not white, non-inflamed papules. It is often caused by comedogenic products or steroids, not typically by peels themselves.

• (C) Closed comedones: These are non-inflammatory acne lesions (whiteheads) that are softer and larger than milia. They are part of acne vulgaris, not a new eruption post-peel.

• (D) Allergic contact dermatitis: Would cause pruritus, erythema, and scaling, not asymptomatic white papules.

• (E) Viral molluscum: Presents as umbilicated, pearly papules that can spread. It is caused by a poxvirus and is not related to peeling.

Management:

• Reassurance: Milia are benign and often resolve spontaneously.

• Treatment: If desired, they can be easily extracted with a sterile needle or comedone extractor.

• Prevention: Use non-comedogenic moisturizers post-peel and encourage gentle exfoliation once healing is complete.

Prognosis:
Excellent; milia are a temporary and manageable side effect.

Note: Milia are a common, expected sequela of procedures that disrupt the epidermis, like chemical peels, dermabrasion, or laser resurfacing. They result from rapid re-epithelialization and occlusion. Differentiating them from acne is important to avoid unnecessary treatments like antibiotics. Patient education is key to managing expectations post-procedure.