Aesthetic Dermatology MCQ - Chemical peels in patients with skin of colour

A 42-year-old woman with Fitzpatrick skin type V and a history of melasma presents for consultation regarding chemical peels. She has previously experienced postinflammatory hyperpigmentation (PIH) after a microdermabrasion procedure. Which of the following peeling agents is the safest first choice for her, considering its efficacy and low risk of causing PIH?

A) Salicylic acid 20-30%
B) Trichloroacetic acid (TCA) 35%
C) Glycolic acid 70%
D) Jessner's solution
E) Pyruvic acid 50%

Correct Answer: A) Salicylic acid 20-30%

Explanation

This question addresses the critical consideration of performing chemical peels in patients with skin of color (Fitzpatrick types IV-VI), who are at high risk for postinflammatory hyperpigmentation (PIH).

Why Salicylic Acid is the Safest Choice:

• Mechanism: Salicylic acid is a beta-hydroxy acid (BHA) that is lipid-soluble. This allows it to penetrate into sebaceous follicles, making it excellent for acne and melasma. It is superficial and causes epidermolysis without significant inflammation.

• Low Risk of PIH: Its anti-inflammatory properties and superficial action result in minimal risk of PIH, making it the safest peel for darker skin types.

• Efficacy for Melasma: It is effective for treating melasma, especially the superficial component, by promoting exfoliation and reducing pigmentation.

Why the Other Agents Are Higher Risk:

• (B) TCA 35%: A medium-depth peel that causes significant inflammation and protein coagulation. It carries a high risk of PIH in skin types IV-VI and is generally avoided in these patients.

• (C) Glycolic acid 70%: An alpha-hydroxy acid (AHA) that can be effective but is water-soluble and may cause more irritation. It requires careful neutralization and has a higher risk of PIH compared to salicylic acid.

• (D) Jessner's solution: Contains resorcinol, salicylic acid, and lactic acid. While it is superficial, resorcinol can cause allergic reactions and irritation, increasing the risk of PIH.

• (E) Pyruvic acid 50%: An alpha-keto acid that is more irritating and less predictable. It has a higher potential for causing PIH and is not recommended as a first-line agent in skin of color.

General Principles for Peels in Skin of Color:

1. Choose Superficial Peels: Salicylic acid, mandelic acid, and low-concentration glycolic acid are preferred.

2. Pre-Treatment Priming: Use hydroquinone 4% and/or tretinoin for 4-6 weeks before the peel to suppress melanocyte activity and reduce PIH risk.

3. Sun Protection: Strict, broad-spectrum SPF 50+ use is mandatory.

4. Test Spot: Perform a test spot in an inconspicuous area to assess the skin's response.

5. Avoid Deep Peels: Phenol and high-concentration TCA are contraindicated due to the high risk of scarring and dyspigmentation.

Prognosis:
With careful agent selection and patient preparation, chemical peels can be performed safely and effectively in skin of color. Salicylic acid peels are a cornerstone of treatment for acne and melasma in these patients.

Note: The history of PIH after microdermabrasion indicates that this patient's skin is particularly prone to dyspigmentation. Therefore, the least inflammatory option (salicylic acid) is ideal. Always prioritize safety over aggressiveness in patients with skin of color.