Skin pigmentation and the sun
Melanin biology, UV exposure and hyperpigmentation
How skin makes pigment
Key takeaway for patientsPigment is the skin’s own sun protection, and dark patches are that system working unevenly. Sun protection is the foundation of every approach, and a mark that changes needs a medical look.
Skin color comes from melanin, made by melanocytes at the base of the epidermis. The enzyme tyrosinase drives its production inside small packages called melanosomes, which are passed to the surrounding skin cells and sit over their nuclei like a cap, shielding DNA from ultraviolet light.
UV exposure increases the production of melanin; this is tanning. Uneven or excessive production causes hyperpigmentation: sun spots, melasma, which is influenced by hormones, and the dark marks left after inflammation.
Key steps in pigmentation
- UV exposure
- DNA damage in skin cells triggers a signal.
- Melanocyte activation
- Signals from the surrounding skin cells switch melanocytes on.
- Melanin synthesis
- Tyrosinase converts the amino acid tyrosine into melanin.
- Transfer
- Melanosomes move into the surrounding cells and shield their nuclei.
Factors that drive hyperpigmentation
Pigment becomes uneven for several reasons:
- Ultraviolet and visible light
- The main driver, and it adds up over the years.
- Hormones
- Pregnancy and hormonal contraception are linked with melasma.
- Inflammation
- Acne, eczema or injury can leave dark marks.
- Skin type and genetics
- Set how readily the skin makes pigment.
Clinical management and physician guidance
Assessment establishes what kind of pigmentation it is, and that nothing more serious is present.
- Skin assessment
- The pattern and depth of pigment, with dermoscopy where needed.
- Physician-guided care
- Sun protection first; other care as your physician decides, with dermatology referral where indicated.
- Monitoring and follow-up
- Any mole or patch that changes is reviewed promptly.
Research focus in pigment biology
| Core focus area | Biological target | Clinical relevance |
|---|---|---|
| Melanin synthesis | Tyrosinase | Production of pigment |
| Melanocyte signaling | The MC1R receptor | Skin type and the response to UV |
| Pigment transfer | Melanosomes and keratinocytes | Distribution of pigment |
| Photoprotection | DNA damage and repair | Protection against UV injury |
Frequently asked questions
- Why do dark patches appear?
- Melanocytes make more pigment, or distribute it unevenly, after sun exposure, hormonal change or inflammation.
- Does sunscreen matter if my skin is dark?
- Yes. All skin types are affected by UV, and visible light can also deepen pigmentation.
- When should a mark be checked?
- When a mole or patch changes in size, shape or color, bleeds, or looks different from the others.
Academic references and literature
- Lin JY, Fisher DE (2007). Melanocyte biology and skin pigmentation. Nature, 445(7130), 843-50. PMID 17314970.
- Brenner M, Hearing VJ (2008). The protective role of melanin against UV damage in human skin. Photochem Photobiol, 84(3), 539-49. PMID 18435612.
- Handel AC, Miot LD, Miot HA (2014). Melasma: a clinical and epidemiological review. An Bras Dermatol, 89(5), 771-82. PMID 25184917.
This guide belongs to the Skin Health program