Aesthetic Dermatology MCQ - Peeling related Postinflammatory hyperpigmentation

A 35-year-old woman with Fitzpatrick skin type IV undergoes a series of glycolic acid peels for melasma. Two weeks after her second peel, she develops dark brown, irregular patches on her cheeks and forehead. She reports diligent sun protection use. Which of the following is the most likely cause and the first-line intervention for this condition?

A) Postinflammatory hyperpigmentation; hydroquinone 4% cream
B) Melasma recurrence; switch to salicylic acid peels
C) Allergic contact dermatitis; topical corticosteroid
D) Persistent erythema; pulsed dye laser
E) Infection; oral antibiotics

Correct Answer: A) Postinflammatory hyperpigmentation; hydroquinone 4% cream

Explanation

This presentation is classic for postinflammatory hyperpigmentation (PIH), a common complication of chemical peels in patients with darker skin types (Fitzpatrick III-VI).

Key Features of PIH:

• Appearance: Dark brown, irregular patches (increased melanin) in areas of previous inflammation or injury.

• Timing: Develops days to weeks after an inflammatory stimulus, such as a chemical peel.

• Pathophysiology: Peels cause controlled inflammation, which can trigger melanocytes to produce excess melanin. This is especially pronounced in darker skin types due to inherently more active melanocytes.

• Risk Factors: Fitzpatrick skin types IV-VI, aggressive peeling, inadequate sun protection, and certain peel types (e.g., deeper peels or those causing significant inflammation).

First-Line Intervention: Topical Hydroquinone

• Mechanism: Hydroquinone is a tyrosinase inhibitor that reduces melanin production.

• Protocol: Hydroquinone 4% cream applied twice daily to affected areas is first-line for treating PIH.

• Combination Therapy: Often used with a topical retinoid (e.g., tretinoin) to enhance epidermal penetration and a mid-potency corticosteroid (e.g., fluocinolone) to reduce inflammation (e.g., in Kligman's formula).

Why Not the Other Options?

• (B) Melasma recurrence: While melasma can recur, the timing (2 weeks post-peel) and pattern (directly following inflammation) are more indicative of PIH. Salicylic acid peels are better for acne but not first-line for melasma or PIH.

• (C) Allergic contact dermatitis: Would present with pruritus, erythema, and scaling, not hyperpigmented patches without active inflammation.

• (D) Persistent erythema: Would appear as redness, not brown patches. Pulsed dye laser targets erythema, not hyperpigmentation.

• (E) Infection: Would present with pain, pustules, or exudate, not asymptomatic hyperpigmentation.

Prevention and Management:

• Pre-peel Priming: Use hydroquinone or retinoids for 4-6 weeks before peeling to suppress melanocyte activity.

• Sun Protection: Strict, broad-spectrum SPF 50+ is non-negotiable to prevent UV-induced melanocyte stimulation.

• Gentle Peeling: Consider superficial peels (e.g., salicylic acid) with less risk of PIH in darker skin.

Prognosis:
PIH can be stubborn but often improves with consistent treatment over months. Relapse is common if triggers are not avoided.

Note: PIH is the most common complication of chemical peels in skin of color. The key to management is prevention through proper patient selection, priming, and sun protection. When it occurs, early intervention with hydroquinone is essential. Always differentiate PIH from melasma, as their management overlaps but may differ in approach.