Pigmentation Disorders

❍ At a glance

• Across all pigmentation conditions, presentation differs between Fitzpatrick skin types, and clinical significance and emotional impact is frequently greater in patients with Fitzpatrick types IV-VI (including many Maori, Pacific, and East Asian patients). Pattern recognition skills developed in fair-skinned populations may not translate reliably.
• Melasma: high-factor broad-spectrum photoprotection is mandatory and ongoing - it is treatment, not just prevention. Topical azelaic acid 20% is first-line and safe in pregnancy.
• PIH: the primary treatment is addressing the underlying inflammation. Persistent eczema or active acne generating ongoing PIH should be treated aggressively. Improvement is slow - counsel patients to assess at six months.
• For any pigmented lesion where malignancy cannot be excluded clinically, dermoscopy or urgent referral takes priority over treating a pigmentation disorder.

❍ Conditions

• Melasma - symmetrical, irregular brown-grey macules predominantly over the cheeks, upper lip, forehead, and mandible. Far more common in women (particularly during pregnancy or on the COCP) and in those with Fitzpatrick types III-V. UV exposure is the primary driver and trigger for relapse. Management: high-factor broad-spectrum photoprotection (mandatory and ongoing), topical azelaic acid 20% (first-line, safe in pregnancy), hydroquinone 2-4% (effective but not widely available OTC in NZ; not recommended in pregnancy), topical retinoids (adapalene or tretinoin - not in pregnancy). Triple combination creams (hydroquinone + tretinoin + steroid) have good evidence but require dermatology oversight. Relapse on sun re-exposure is universal - emphasise that sun protection is treatment, not just prevention.
• Post-inflammatory hyperpigmentation (PIH) - dark marks persisting after resolution of skin inflammation from acne, eczema, insect bites, trauma, or any inflammatory skin condition. More pronounced and longer-lasting in Fitzpatrick types IV-VI. The primary treatment is addressing the underlying inflammation - persistent eczema or active acne generating ongoing PIH should be treated aggressively. For existing PIH: photoprotection (essential), topical azelaic acid 20%, adapalene gel. Improvement is slow - counsel patients to assess at six months. Niacinamide 5% (in many OTC moisturisers) has modest evidence for reducing PIH over time and is well tolerated.
• Solar lentigines - well-demarcated, uniformly pigmented flat macules on sun-exposed skin (dorsal hands, face, décolletage), often called "age spots." The key clinical task is distinguishing from lentigo maligna (irregular border, variable pigmentation, enlarging) - any atypical lentigo should be reviewed by a dermoscopist or referred. Benign lentigines can be treated with topical retinoids or azelaic acid; cryotherapy, laser, and IPL are effective cosmetically but not funded in New Zealand.
• Vitiligo - acquired depigmentation from autoimmune destruction of melanocytes. Chalk-white macules with well-defined margins; Wood's lamp accentuates contrast markedly. Assess for associated autoimmune conditions (thyroid disease most commonly, type 1 diabetes, Addison's disease). Segmental vitiligo (unilateral, dermatomal) is less likely to spread; non-segmental (generalised) vitiligo is progressive. Treatment options in NZ are limited: topical tacrolimus 0.1% (off-label, useful for face and flexures), narrowband UVB phototherapy (available through dermatology, evidence-based for repigmentation), and topical ruxolitinib (JAK inhibitor, TGA approved but not yet PHARMAC subsidised). Refer to dermatology if the patient wishes to pursue active treatment.¹

❍ Practical approach in primary care

The first step is accurate diagnosis - many patients present having already tried multiple products, some inappropriate. A brief history (onset, distribution, relationship to sun or inflammation, medications including COCP, pregnancy history, family history) and examination under good lighting is usually sufficient to categorise the condition. For any pigmented lesion where malignancy cannot be excluded clinically, dermoscopy or urgent referral takes priority. For benign pigmentary conditions, the core GP role is: confirm diagnosis, address treatable underlying causes, prescribe evidence-based topicals, and set realistic expectations. Effective treatment for pigmentation is slow - months, not weeks - and most conditions will return without ongoing photoprotection.²