Clinical Conditions That Cause Melasma
Melasma is predominantly attributed to ultraviolet (UV) exposure and hormonal influences, occurring most commonly in females and darker skin types, with pregnancy, oral contraceptives, and thyroid dysfunction being the primary clinical conditions that trigger its manifestation 1.
Primary Triggering Conditions
Hormonal Factors
- Pregnancy - One of the most common triggers, with melasma frequently developing during gestation due to hormonal fluctuations 2
- Oral contraceptives and hormone replacement therapy - Exogenous hormones can precipitate melasma in susceptible individuals 3, 2
- Thyroid dysfunction - Thyroid disorders have been implicated as a contributing factor 4
Dermatologic and Systemic Conditions
- Chronic inflammatory skin processes - Ongoing inflammation can trigger pigmentary changes leading to melasma 2
- Rosacea - This condition is associated with melasma, particularly in fair-skinned individuals, though it can occur in all skin types 5, 6
Medication-Induced
- Photosensitizing drugs - Various medications that increase photosensitivity can precipitate melasma 2
- Systemic steroids - Corticosteroid use has been associated with melasma development 2
- Isotretinoin - This systemic retinoid used for severe acne can disrupt skin function and potentially contribute to pigmentary changes 5
Contributing Pathophysiologic Factors
Environmental and Oxidative Stress
- UV radiation exposure - The most significant environmental trigger, causing oxidative stress and melanocyte stimulation 1, 7
- Visible light (VL) exposure - Recent evidence shows VL can also trigger melasma, particularly in darker skin types 8
- Oxidative stress - Disequilibrium between reactive oxygen species and antioxidants plays a key role in hyperpigmentation 4
Genetic Predisposition
- Family history - Over 40% of patients report relatives with melasma, indicating strong genetic susceptibility 2
- Darker skin phenotypes - Fitzpatrick skin types III-V are at higher risk 3, 2
Important Clinical Caveats
The condition should be understood as a photoaging disorder affecting genetically predisposed individuals rather than purely a hormonal condition 7. This distinction is critical because it shifts treatment focus to include photoprotection and antioxidant strategies alongside hormonal management.
The pathophysiology involves multiple skin layers: epidermal barrier dysfunction, basement membrane damage, dermal solar elastosis, vascular changes, mast cell infiltration, and senescent fibroblast activity 9, 8. This explains why melasma is notoriously difficult to treat and requires comprehensive management addressing UV protection, hormonal factors, and skin barrier restoration 1.
Key pitfall to avoid: Do not attribute melasma solely to hormonal causes. While hormones are important triggers, UV exposure and genetic predisposition are equally critical, and treatment must address all factors simultaneously for optimal outcomes 7, 3.