58-year-old female presented with brownish discoloration of the forehead. Her facial skin is fair, but her forehead has brownish discoloration. It is uniform discoloration from right to left and from top to bottom. Bottom area is up to the eyebrow. No papules, no eruptions, no pettechia, not purpura, no history of trauma, no swelling, no redness, no other symptoms. Patient says she had a history of prolonged exposure to sun in the last couple of days.
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Clinical Assessment: Melasma (Centrofacial Pattern)
This presentation is highly consistent with melasma - specifically the centrofacial pattern, which is the most common variant (63% of cases).
Why This Fits
The combination of findings aligns precisely with melasma's classic profile:
| Feature | This Patient | Melasma Profile |
|---|---|---|
| Age/Sex | 58-year-old female | Predominantly premenopausal/perimenopausal women |
| Location | Forehead, bilateral, uniform | Centrofacial pattern - forehead is primary site |
| Border | Up to eyebrows (sparing periorbital) | Melasma classically spares periorbital skin |
| Color | Uniform brownish | Light-brown to dark-brown macular pigmentation |
| Morphology | No papules, no eruptions | Pure macular pigmentation - no primary lesions |
| Trigger | Prolonged sun exposure | Sun exposure is the primary trigger |
Clinical images from Fitzpatrick's Dermatology showing the classic forehead/facial distribution:
Pathophysiology
Sun exposure is the primary trigger for melasma. UV light stimulates biologically active melanocytes to overproduce melanin. Melasma patients have a lower minimal erythema dose (MED) to UV light and pigment more easily with UV exposure. At the molecular level, melasma-affected skin shows reduced WIF-1 (Wnt antagonist) expression, resulting in increased Wnt signaling that stimulates melanogenesis. Solar elastosis is more marked in affected areas than in unaffected facial skin. - Andrews' Diseases of the Skin, p. 993
The 58-year-old age and female sex also fit: at menopause, hormonal influences (endogenous estrogen changes) can contribute even without exogenous hormone use.
Differential Diagnoses to Consider
While melasma is the leading diagnosis, briefly consider:
- Postinflammatory hyperpigmentation (PIH): Requires a prior inflammatory event (eczema, acne, trauma) - absent here
- Drug-induced hyperpigmentation: Certain medications (phenytoin, amiodarone, tetracyclines) - no drug history mentioned; must be asked
- Addison's disease: Diffuse hyperpigmentation but also involves mucous membranes, non-sun-exposed areas, and is accompanied by systemic symptoms (fatigue, hypotension)
- Contact/photocontact dermatitis: Typically associated with redness and pruritus before pigmentation, often patchy
- Phytophotodermatitis: History of plant/citrus exposure + sun; usually streaky/geometric pattern
Recommended Workup
- Wood's lamp examination: Epidermal melasma (most common) shows enhancement under Wood's lamp; dermal melasma does not enhance. Most cases show mixed epidermal and dermal melanin.
- Hormone history: Oral contraceptive use, HRT, thyroid dysfunction
- Medication review: Phenytoin, finasteride (and other potential culprits)
- Dermoscopy: Can help characterize depth and differentiate from mimics
Management
Photoprotection is the cornerstone and must be started immediately:
- Broad-spectrum sunscreen (UVA + UVB coverage, SPF 30+) applied daily
- Physical sunscreens (zinc oxide, titanium dioxide) preferred; visible light protection is also needed since visible light can trigger pigmentation
- Sunscreen alone modestly improves melasma AND enhances the efficacy of bleaching agents
First-line topical therapy:
- Hydroquinone 2-4% - gold standard tyrosinase inhibitor; available OTC at 2%, prescription at 4%
- Kligman's formula (triple combination): hydroquinone + tretinoin + mild topical corticosteroid - the most effective topical regimen available. Twice-weekly maintenance application is effective.
- Tretinoin alone reduces melasma but is less effective than hydroquinone as monotherapy
Second-line / adjunctive agents (when hydroquinone is insufficient):
- Azelaic acid (tyrosinase inhibitor)
- Kojic acid (inhibits tyrosinase via copper chelation)
- Tranexamic acid (topical or oral - plasmin inhibition + antioxidant mechanism)
- Arbutin
- Methimazole
Caution with procedural treatments:
Peels (glycolic acid, TCA, salicylic acid) and laser/light modalities should be used cautiously - they carry a risk of worsening pigmentation, especially in darker skin types. IPL can improve melasma but has a high relapse rate. Q-switched Nd:YAG laser can paradoxically increase pigmentation. - Andrews' Diseases of the Skin, p. 993-994
Key Counseling Points for This Patient
- Sun avoidance and year-round photoprotection are non-negotiable - melasma worsens with every UV exposure
- This is a chronic, relapsing condition - not a single-treatment cure
- Prognosis is generally favorable with consistent photoprotection and appropriate topical therapy
- Enquire about menopausal hormone use, as HRT is a known exacerbating factor; discontinuation rarely clears pigmentation quickly but is still worth discussing
Sources: Andrews' Diseases of the Skin: Clinical Dermatology, p. 993-994; Fitzpatrick's Dermatology, 9th ed., p. 1409; Harrison's Principles of Internal Medicine 22E
What if it is untreated, that is, she uses only sunscreens, but no treatments like hydroquinone? What is the prognosis of melasma?
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Prognosis of Melasma with Sunscreen Only (No Active Treatment)
The short answer: sunscreen alone produces modest improvement at best, but melasma will not resolve on its own - and in this patient's situation, recurrence and persistence are the expected course.
1. Melasma is a Chronic, Relapsing Disorder
The fundamental nature of melasma is important to understand upfront. As stated plainly in Dermatology 2-Volume Set (Bolt et al.):
"Melasma is a complex and therapeutically challenging disorder... While treatment regimens boast varying degrees of improvement, recurrence is the norm despite recommended measures such as strict sun protection."
And from the 2022 update on melasma treatment (Cassiano et al., PMID 35906506):
"Melasma is a prevalent chronic relapsing pigmentary disorder... there is currently no curative treatment available for melasma."
This means even with optimal treatment including hydroquinone, patients routinely relapse. With sunscreen alone, the trajectory is even less favorable.
2. What Sunscreen Alone Actually Does
Sunscreen is not a passive measure - it has real, documented effects on melasma:
- Prevents worsening: By blocking UV light (the primary trigger), sunscreen prevents new melanin stimulation and slows progression
- Modest improvement over time: Broad-spectrum sunscreen use can lessen melasma severity on its own, but the improvement is limited compared to active depigmenting agents
- Enhances any future treatment: If the patient later starts hydroquinone or other agents, sunscreen dramatically amplifies their efficacy
However, a critical nuance from recent evidence (Morgado-Carrasco et al. 2022, PMID 35229368):
"The majority of melasma patients do not adequately follow photoprotection recommendations... Intensive use of a broad-spectrum sunscreen can prevent melasma in high-risk individuals, can lessen melasma severity... and can reduce relapses - but does not eliminate the underlying pathology."
3. The Problem of Visible Light and UVA1
Standard chemical sunscreens (which block UVB and short UVA) are insufficient for melasma. Fitzpatrick's notes that visible light - particularly high-energy visible light (HEVL) - and long-wave UVA1 play a key role in melasma pathophysiology, especially in darker-skinned individuals. Standard sunscreens do not block these wavelengths. Only tinted sunscreens (containing iron oxides) protect against HEVL. If this patient is using a standard sunscreen, even "perfect" application may still allow ongoing pigment stimulation.
4. The Dermal Melanin Problem
Melasma pigmentation is not solely epidermal. Most cases have mixed epidermal and dermal melanin. Dermal melanophages (melanin-laden macrophages in the dermis) respond very poorly to topical agents - and essentially not at all to sunscreen alone. Dermal melasma tends to be:
- More persistent
- Slower to fade
- More resistant to any treatment
Since this patient is 58 years old with likely longstanding sun damage, there is a reasonable chance she has accumulated dermal melanin, which will not improve with sunscreen-only management.
5. What to Expect Over Time Without Treatment
| Timeframe | Likely Outcome with Sunscreen Only |
|---|---|
| Short-term (weeks-months) | Pigmentation stabilizes; may lighten slightly if sun is avoided strictly |
| With continued incidental sun exposure | Pigmentation recurs or deepens each summer/sun exposure |
| Long-term (years) | Chronic persistence; some cases may partially fade in winter months but darken again seasonally - a "waxing and waning" pattern |
| Post-menopause | Modest spontaneous improvement is possible as estrogen levels decline, but pigmentation typically does not disappear completely |
The one scenario where melasma does spontaneously resolve is melasma of pregnancy - which typically clears within a few months of delivery. In non-pregnancy melasma (as in this patient), spontaneous complete resolution is uncommon. - Andrews' Diseases of the Skin, p. 993
6. Quality of Life Impact
Even if the pigmentation does not worsen, leaving it untreated carries a documented psychosocial cost. Fitzpatrick's explicitly states:
"The negative impact on quality of life has been documented repeatedly in the literature; consequently, symptoms of depression and anxiety need to be explored by the treating clinician."
Bottom Line for This Patient
With sunscreen alone, she can expect:
- No cure and likely no significant lightening
- Seasonal fluctuation - darker in summer, slightly lighter in winter
- Gradual persistence of dermal melanin over years that becomes progressively harder to treat
- Partial natural improvement after menopause is possible but unreliable and incomplete
The practical recommendation is to counsel her that sunscreen is necessary but not sufficient - it is the foundation that all other therapies are built upon, not a standalone treatment. Starting a tyrosinase inhibitor (hydroquinone 2-4%, or azelaic acid as a gentler alternative) now, while the pigment is still predominantly epidermal, gives the best long-term outcome. Delaying treatment allows dermal deposition to accumulate, making the condition progressively harder to reverse.
Sources: Andrews' Diseases of the Skin, p. 993; Dermatology 2-Volume Set 5e, p. 2859; Fitzpatrick's Dermatology Vol. 1-2, p. 1409; Morgado-Carrasco et al. (2022) PMID 35229368; Cassiano et al. (2022) PMID 35906506
Cause of melasma
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Causes of Melasma
The pathogenesis is not completely understood, but melasma is recognized as a multifactorial disorder driven by the interaction of three main domains: UV/visible light, hormones, and genetic predisposition. These act on biologically hyperactive melanocytes to produce excess melanin.
1. Ultraviolet and Visible Light (Primary Trigger)
UV light is the single most important trigger for melasma. Evidence supporting this:
- Melasma affects the face - exclusively sun-exposed areas - and worsens predictably in summer
- Melasma patients have a lower minimal erythema dose (MED) to UV, meaning their skin responds to UV at lower intensities than normal
- They pigment more easily and more intensely with UV exposure
- Solar elastosis (UV-induced dermal damage) is more marked in melasma-affected skin than in adjacent unaffected facial skin
- The condition spontaneously lightens in winter when UV exposure is reduced
At the molecular level:
- Melasma skin shows reduced WIF-1 (Wnt inhibitory factor-1, a Wnt antagonist) expression
- This leads to increased Wnt signaling, which directly stimulates melanogenesis (melanin production)
- Visible light - particularly high-energy visible light (HEVL, the blue-violet spectrum) - and long-wave UVA1 have also been specifically implicated, especially in darker-skinned individuals. This is why standard sunscreens that only block UVB/short-UVA can be insufficient.
- Increased vascular endothelial growth factor (VEGF) and increased vascularity in lesional epidermis suggest a vascular component to pathogenesis as well - Fitzpatrick's Dermatology, p. 1409
2. Female Sex Hormones (Second Most Important Trigger)
Melasma is predominantly a disease of women (>90% of cases), and hormonal influences are central:
| Hormonal State | Effect |
|---|---|
| Pregnancy | Common trigger ("mask of pregnancy" / chloasma); usually resolves after delivery |
| Oral contraceptive (OC) use | Strong association; importantly, stopping OCs rarely clears the pigmentation - it can persist for many years |
| Hormone replacement therapy (HRT) | Triggers or worsens melasma at menopause |
| Other endocrinologic disorders | Can be associated (e.g. thyroid dysfunction) |
Estrogen and progesterone directly stimulate melanocyte activity. The fact that pregnancy melasma resolves after delivery (while OC/HRT melasma often does not) suggests that the duration and type of hormonal stimulus matters. - Andrews' Diseases of the Skin, p. 993
3. Genetic Predisposition
- Strong racial/ethnic clustering: predominantly affects East, West, and Southeast Asians; Hispanics; and Black individuals - especially those with Fitzpatrick skin types IV-V living in high UV-intensity regions
- Up to 30% of middle-aged Asian females have subtle melasma detectable under UV examination
- There is an association between the number of melanocytic nevi (a marker of melanocyte proliferative activity) and the development of melasma
- Family history is common - suggesting a significant hereditary component
4. Drugs
Certain medications can trigger or worsen melasma independent of hormones:
- Phenytoin (anti-epileptic)
- Finasteride (in males - a rare but documented cause)
- Phototoxic drug reactions (e.g. tetracyclines, amiodarone) can cause similar facial pigmentation and may overlap with melasma
5. Age and Cumulative Sun Damage
- Prevalence increases with age in both men and women
- Cumulative UV exposure over a lifetime progressively sensitizes facial melanocytes
- Older patients tend to have a greater proportion of dermal melanin (deposited in dermal melanophages), which is more resistant to treatment
Summary Diagram of Causation
Genetic predisposition (skin type IV-V, family history)
+
UV light / visible light → WIF-1 ↓ → Wnt ↑ → Melanogenesis ↑
+ ↓
Female hormones (pregnancy, Hyperactive melanocytes
OCP, HRT) ↓
+ Excess melanin in epidermis
Drugs (phenytoin, finasteride) ± dermis (melanophages)
↓
MELASMA (brown patches)
Why Melasma Is Hard to Eradicate
Even after the trigger is removed, the melanocytes remain biologically hyperactive. Dermal melanophages are essentially permanent once formed - phagocytic cells that have engulfed melanin do not simply release it. This explains why melasma can persist for years after stopping OCP, and why sun protection alone is rarely curative.
Sources: Andrews' Diseases of the Skin, p. 993; Fitzpatrick's Dermatology Vol. 1-2, p. 1409; Dermatology 2-Volume Set 5e, p. 1343
Can this condition be just a sunburn? How do you differentiate?
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Excellent. I now have a thorough picture of sunburn pathophysiology and clinical features to directly compare with melasma. Here is a focused, clinically useful differentiation:
Can This Be a Sunburn? Differentiating Melasma from Sunburn/Sun Tan
This is a very good clinical question, especially since the patient does have a recent sun exposure history. The short answer is: no, a straightforward sunburn does not explain this presentation - and the two can be separated clearly on clinical grounds alone.
What a Sunburn Actually Looks Like
Sunburn is the cutaneous reaction to UV radiation in excess of the erythema dose. Its cardinal features are:
- Erythema (redness) - the defining feature, peaking at 12-24 hours after exposure
- Tenderness/pain - the skin hurts to touch
- Edema - especially on the face and extremities
- In severe cases: blistering, chills, fever, nausea, tachycardia, hypotension
- Desquamation - peeling about 1 week later, even in areas that did not blister
- Color is red to pink, not brown
This is primarily mediated by UVB (280-320 nm), which is up to 1000 times more erythemogenic than UVA. - Andrews' Diseases of the Skin, p. (sunburn section)
None of these features are present in this patient. She has no redness, no tenderness, no swelling, no peeling, and no systemic symptoms.
What About Post-Sun Tanning?
After sunburn resolves, or after sub-erythemal UV exposure, the skin undergoes tanning (delayed melanogenesis):
| Phase | Timing | Mechanism | Color |
|---|---|---|---|
| Immediate pigment darkening (IPD) | Within hours | Redistribution/oxidation of pre-existing melanin | Transient gray-brown; fades quickly |
| Delayed tanning | Begins 2-3 days after exposure, peaks ~3 days | New melanin synthesis (UVB-induced DNA damage → CPD formation → melanogenesis) | Brown; lasts 10-14 days |
Could this be just a sun tan? Possibly, if this were a short-lived brown discoloration appearing days after sun exposure on normal skin. But the clinical picture here argues against it:
Side-by-Side Comparison
| Feature | Sunburn / Sun Tan | This Patient's Presentation |
|---|---|---|
| Primary color | Red (acute), then fading brown tan | Brownish - no red phase reported |
| Redness | Yes (defining feature) | Absent |
| Pain / tenderness | Yes | Absent |
| Swelling / edema | Common on face | Absent |
| Peeling | Expected ~1 week later | Absent |
| Duration | Tan fades in 10-14 days without further exposure | Melasma persists and does not fade on its own |
| Distribution | Diffuse on all sun-exposed surfaces (whole face, neck, arms) | Confined to forehead with clear lower border at eyebrows; rest of face fair - highly selective |
| Border sharpness | Gradual, corresponds to clothing lines | Melasma borders are sharply demarcated |
| Pre-existing skin | Normal baseline skin pigmentation | Fair baseline skin - the forehead stands out discretely |
| Pattern | Uniform across all exposed areas | Uniform within a specific anatomical zone (forehead), sparing periorbital area |
The Key Differentiating Point: The Distribution
The single most telling feature here is selective forehead involvement with a distinct lower border at the eyebrows, while the rest of the face remains fair.
A sunburn or sun tan does not behave this way. The entire face - cheeks, nose, chin - would all tan together if this were UV-induced pigmentation from sun exposure alone. The highly selective, anatomically bounded forehead pattern strongly favors melasma (centrofacial pattern) over a generalized photo-response.
Additionally, sun tans are transient - delayed melanogenesis lasts only 10-14 days. If the discoloration is stable and persists beyond two weeks of sun avoidance, that essentially rules out simple tanning and confirms a structural hyperpigmentation disorder like melasma.
Sunburn as a Trigger, Not the Cause
It is important to recognize that sun exposure can precipitate or worsen melasma - so the patient's recent prolonged sun exposure likely acted as the trigger that unmasked or intensified pre-existing melasma, rather than causing a sunburn. This is mechanistically consistent: UV light stimulates overactive melanocytes in melasma-prone skin to produce excess melanin, producing the brownish discoloration without the inflammatory (erythema/pain) component of true sunburn.
Bedside Test: Wood's Lamp
If any doubt remains, a Wood's lamp examination (UV-A lamp in a darkened room) can help confirm:
- Melasma (epidermal type): pigmentation is accentuated/enhanced under Wood's lamp
- Suntan: no significant enhancement under Wood's lamp
- Dermal melasma: no accentuation (but still melasma)
Sources: Andrews' Diseases of the Skin (Sunburn and Solar Erythema section); Dermatology 2-Volume Set 5e, p. 1852; Fitzpatrick's Dermatology, p. 1409
There is no issue on the eyebrows. It's only in the forehead, and there is no redness, itching, swelling, scaling, and she says that it comes and goes every year during the summer period.
This additional history is very important and actually strengthens the diagnosis of melasma considerably. Let me explain why each new piece of information fits:
How This New History Refines the Diagnosis
1. "Comes and goes every year during summer" - This is the Hallmark of Melasma
This seasonal relapsing pattern is the classic natural history of melasma. As Fitzpatrick's states directly:
"Melasma is a chronic and relapsing condition with exacerbations during pregnancy, sun or visible light exposure, and with certain hormonal treatments."
Melasma worsens in summer (high UV exposure) and lightens in winter (reduced UV). This cyclical, seasonal behavior over multiple years is not seen in sunburn, postinflammatory hyperpigmentation, or contact dermatitis - it is essentially pathognomonic for melasma.
2. "No issue on the eyebrows" - Confirms Periorbital Sparing
Fitzpatrick's specifically notes that melasma spares the periorbital skin, lips, neck, and ears. The fact that the eyebrows themselves are unaffected - with pigmentation running uniformly across the forehead right down to the eyebrow line but not onto or around the eyes - is precisely the border pattern expected in centrofacial melasma. This is a feature that no other common diagnosis produces in this way.
3. No Redness, No Itching, No Swelling, No Scaling - Rules Out All Inflammatory Differentials
These negatives are clinically powerful. Let's use them to eliminate the remaining differentials:
| Condition | Why Now Ruled Out |
|---|---|
| Sunburn | Always has erythema and tenderness - absent here |
| Contact dermatitis | Requires erythema, itch, and often scaling |
| Photocontact / phototoxic dermatitis | Erythema and burning are defining features |
| Seborrheic dermatitis | Has scaling and redness, forehead is a common site but scaling is mandatory |
| Tinea versicolor | Has fine scaling; usually trunk > face |
| Lichen planus pigmentosus | Has an inflammatory phase with violaceous lesions |
| Riehl's melanosis (pigmented contact dermatitis) | History of erythema, burning precedes pigmentation |
All inflammatory and reactive causes are excluded by the complete absence of any inflammatory symptoms or signs - past or present.
4. Confirmed Diagnosis: Melasma, Centrofacial Pattern
Pulling everything together:
| Clinical Feature | Significance |
|---|---|
| 58-year-old female | Classic demographic |
| Uniform brown discoloration, forehead only | Centrofacial pattern |
| Sharp lower border at eyebrow line | Periorbital sparing - characteristic |
| Eyebrows themselves unaffected | Confirms selectivity of melanocyte involvement |
| No papules, redness, itch, swelling, scaling | Pure macular pigmentation, no inflammation |
| Triggered by sun exposure | UV is the primary precipitant |
| Recurs every summer, fades in winter | Chronic seasonal relapsing course - the definitive feature |
The seasonal "comes and goes" history alone essentially clinches this. No other common forehead pigmentation disorder behaves with this predictable summer-worsening, winter-fading annual cycle over years.
What This Seasonal Pattern Also Tells You Clinically
- The pigmentation is likely still predominantly epidermal (not yet deeply dermal), since it is still capable of fading in winter. Dermal melasma tends to be more persistent year-round.
- This is a favorable prognostic sign - epidermal melasma responds better to topical therapy.
- However, each successive summer cycle risks driving more melanin into the dermis (melanophages), making it progressively harder to treat over time. This is the argument for not waiting too long to start treatment.
Management Implication of This Pattern
Given this is a recurring seasonal condition for this patient, the management approach should be:
- Year-round broad-spectrum tinted sunscreen (iron oxide-containing, to block visible/HEVL) - not just in summer
- Pre-emptive topical treatment starting before or at the beginning of summer, rather than waiting for pigmentation to appear
- Maintenance therapy in winter to prevent deepening of dermal deposition over years
The seasonal history makes this a very manageable case - she has a predictable trigger, her melanocytes are still UV-responsive rather than constitutively overactive, and her pigment still has the capacity to fade.
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