DERM 15: Post-Inflammatory Hyperpigmentation (PIH) Flashcards
What is post-inflammatory hyperpigmentation (PIH)?
overproduction of melanin caused by inflammation after trauma – acne, bug bites, skin cuts/abrasions, eczema, psoriasis
What skin type is more susceptible to PIH?
darker skin tones
What is melasma?
tan or dark skin discolouration
- causes: genetic, hormonal, pregnancy-induced, UV-induced, head-induced
What are solar lentigines?
sun/liver/age spots
- UV-induced
What is the primary role of melanin? (2)
pigmentation
photoprotection:
- UV light: protects epidermal cells from all UV light (UVA/B), blue light
- reactive oxygen species (ROS): acts as antioxidant by scavenging ROS, which can cause cellular damage as a result of UV light damage
How is melanin produced?
- synthesized within melanocytes (in basal layer of epidermis) in membrane-bound organelles called melanosomes
- melanogenic pathway that occurs within melanosomes produces eumelanin (tones – brown, black) and pheomelanin (hues – red, yellow)
How is melanin synthesized?
activation phase (stage 1 + 2):
- melanocyte-stimulating hormone (MSH) activates melanin production
- MSH binds to hormone receptor on melanocyte
- activates melanin synthesis
Describe the pathophysiology of hyperpigmentation and how it relates to darker skin tones.
- inflammatory mediators (prostaglandins, leukotrienes) stimulate melanocytes and increase melanin synthesis, leading to transfer of pigment in surrounding keratinocytes
- melanin is transported to upper levels of skin through outward growth of keratinocytes
- lesions of PIH can darken with exposure to UV light and various chemicals and medications
What are the goals of therapy?
- protect
- prevent
- correct
Protect
What are the therapies before melanin synthesis? (1)
sunscreen
- year-round SPF 30+
- ↓ UV exposure – limits stress-induced melanin synthesis AND reduces further darkening of existing PIH
- mineral (white casting issues on darker skin tones), chemical or mixed (physical/chemical)
- tinted broad-spectrum sunscreens are ideal
Prevent
What are the therapies before melanin synthesis? (2)
antioxidants
- vitamin C, vitamin E, niacinamide
- prevent cellular damage via ROS – limits stress-induced melanin synthesis
decrease tyrosinase
- vitamin E, retinoids (tretinoin, adapalene, tazarotene)
Correct
What are the therapies during melanin synthesis? (2)
pigment lighteners
tyrosinase inhibitors
- hydroquinone, kojic acid, arbutin, vitamin C, cysteamine, azelaic acid
Correct
What are the therapies after melanin synthesis? (3)
pigment lighteners
melanin transfer inhibitor
- niacinamide
skin cell turnover
- AHA (lactic acid + mandelic acid), BHA, retinoids
What is the recommended application for vitamin C?
- daily in morning, after washing/peels, before other serums
- L-ascorbic acid or magnesium ascorbyl phosphate = better tolerated and more stable
- light-sensitive – opaque, air-tight bottle
- apply to dry skin to avoid irritation
- look for products with pH < 3.5 and vitamin C concentration 10-20%
What is the recommended application for niacinamide?
- once daily, before other serums/actives
- BID application can show results as early as 4 weeks
- 2% for sensitive skin – 5% best if tolerated
- rarely formulated alone – often with other pigmentation-reducing actives or sebum-controlling product
What is the recommended application for hydroquinone?
- BID, max 3 months
- 2% – schedule 2 (pharmacy or medical clinic/aesthetics clinic)
- 4% – Rx
- prolonged use may produce leukoderma
- must use SPF 30+ daily at same time
- contains AHA (glycolic acid and citric acid)
What is the recommended application for cysteamine?
- daily, at least 1 hour after washing area, leave on for 15 min and wash off
- initial: everyday for 16 weeks
- maintenance: two days per week
- apply moisturizer after, keep skin hydrated
- melasma, solar lentigines has more evidence
- available at medical esthetic clinics only
What are some additional counselling points for patients?
- only add one active at a time (once initial tolerance is established)
- find combination products once a set of actives is established as tolerant
- short-term use of topical corticosteroids can lessen amount of skin irritation caused by some skin-lightening products
- use tinted broad-spectrum sunscreen year-round
use tolerated actives regularly - gently exfoliate with chemical peels twice a month, but no more than weekly
- treating inflammatory conditions (eczema, acne) quickly and effectively can help prevent new pigmented areas from forming – consider being aggressive initially in high risk PIH with BHA/BP + retinoids
- anti-inflammatory products – possible ↑ skin production of anti-inflammatory molecules (resveratrol, vitamin E, centella asiatica (gotu kola))
- hyperpigmentation that impacts dermis may take years to fade, sometimes permanent
- medical esthetic procedures can result in significant improvements in shorter time – high % chemical peels, laser therapy, micro-needling with optional plasma rich platelets/PRP (all must stop most Rx and OTC products first)
