Aesthetic Dermatology MCQ - Laser Management of Melasma

9/16/20252 min read

A 35-year-old woman with Fitzpatrick skin type IV presents with symmetric, brownish hyperpigmentation on her malar eminences and forehead. The pigmentation has been persistent for 3 years and worsens with sun exposure. She has used topical hydroquinone 4% with minimal improvement. Which of the following lasers is most appropriate for treating this condition, considering its efficacy and safety profile in darker skin types?

A) Q-switched Nd:YAG laser (1064 nm)
B) Ablative fractional carbon dioxide (CO2) laser
C) Pulsed dye laser (595 nm)
D) Intense pulsed light (IPL)
E) Argon laser

Correct Answer: A) Q-switched Nd:YAG laser (1064 nm)

Explanation

This presentation is classic for melasma, a challenging acquired hyperpigmentation disorder that is more common in women and individuals with Fitzpatrick skin types III-VI. Treatment must be approached cautiously in darker skin due to the high risk of post-inflammatory hyperpigmentation (PIH).

Why Q-Switched Nd:YAG Laser (1064 nm) is Most Appropriate:

Mechanism: The 1064 nm Q-switched Nd:YAG laser delivers nanosecond-domain pulses that target melanin via photothermal and photomechanical effects. The longer wavelength penetrates deeply into the dermis (where melanin in melasma may reside) with reduced melanin competition in the epidermis, lowering the risk of PIH.
Safety in Darker Skin: The 1064 nm wavelength is safer for darker skin types (IV-VI) compared to shorter wavelengths (e.g., 532 nm) or ablative lasers, as it is less absorbed by epidermal melanin.
Efficacy: It is effective for dermal and mixed-type melasma. Low-fluence settings (e.g., 2-3 J/cm²) in multiple sessions can achieve gradual improvement.
Protocol: Often used in combination with topical agents (e.g., hydroquinone, tranexamic acid) for maintenance.

Why Not the Other Options?

(B) Ablative fractional CO2 laser (10,600 nm): Causes significant epidermal injury and has a high risk of PIH and scarring in darker skin types. It is generally avoided in melasma management.
(C) Pulsed dye laser (595 nm): Targets hemoglobin and is used for vascular lesions (e.g., port-wine stains). It is not effective for melanin-based pigmentation like melasma.
(D) Intense pulsed light (IPL): A broadband light source (500-1200 nm) that targets melanin and hemoglobin. However, it carries a high risk of PIH in skin types IV+ due to uncontrolled epidermal heating and is not recommended for melasma in darker skin.
(E) Argon laser (488-514 nm): Emits blue-green light highly absorbed by melanin. It poses an extreme risk of PIH and scarring in dark skin and is obsolete for melasma treatment.

Important Considerations in Melasma Management:

First-line therapy remains topical agents (hydroquinone, retinoids, corticosteroids) and strict sun protection.
Lasers are second-line for refractory cases.
Combination therapy (e.g., low-fluence Nd:YAG with topical tranexamic acid) may enhance results.
Relapse is common, and maintenance therapy is essential.

Prognosis:
Guarded; melasma is chronic and recurrent. Laser treatment can improve but rarely cure the condition, and PIH remains a significant risk.

Note: The Q-switched Nd:YAG laser at 1064 nm is the preferred laser option for melasma in darker skin types due to its deeper penetration and reduced risk of epidermal injury. However, it should be used by experienced practitioners as part of a comprehensive management plan that includes sun protection and topical therapy. Ablative and shorter wavelength devices should be avoided due to the high risk of complications.