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Post-Inflammatory Hyperpigmentation (PIH)

Post-Inflammatory Hyperpigmentation (PIH): Causes, Treatment, and Management

What is PIH?

Post-inflammatory hyperpigmentation (PIH) is a common skin condition characterized by darkened patches that appear after skin inflammation or injury. It manifests as irregular, pigmented areas at the site of previous skin trauma such as acne, eczema, burns, or other inflammatory skin diseases. PIH is more prevalent and severe in individuals with darker skin types (Fitzpatrick skin types III to VI).

Causes of PIH

• Excess melanin production triggered by inflammation or injury, leading to increased pigmentation.
• Melanocyte hypertrophy and melanin transfer to surrounding keratinocytes during inflammatory processes.
• Melanin can be retained in macrophages when basal layer injury occurs, resulting in dermal melanosis or pigment incontinence.
• Sun exposure worsens PIH, darkening pigmented patches.

Pathophysiology

• Inflammatory stimuli stimulate melanocytes to produce excess melanin.
• Melanin deposits gain different depths: in the epidermis (epidermal hypermelanosis) or dermis (dermal melanosis).
• Healing skin results in persistent pigmented patches, which vary from light brown to black.

Treatment and Management

Prevention

• Daily application of broad-spectrum sunscreen (SPF 50+) to minimize UV-induced darkening.
• Cosmetic camouflage to mask hyperpigmented areas temporarily.

Topical Agents

• Hydroquinone: Inhibits tyrosinase, reducing melanin synthesis; most effective for epidermal hyperpigmentation.
• Retinoids (tretinoin, adapalene): Promote skin cell turnover, fade dark spots, and improve skin texture.
• Kojic Acid: Lightens pigmentation by inhibiting melanin production.
• Azelaic Acid: Anti-inflammatory and depigmenting; suitable for sensitive skin.
• Vitamin C: Antioxidant that brightens skin and reduces melanin formation.
• Hydroquinone + Tretinoin: Combination therapy enhances results in many cases.

Cosmetic Procedures

• Chemical Peels: Glycolic, salicylic, or trichloroacetic acid peels remove pigmented epidermal layers.
• Laser Therapy: Q-switched lasers and IPL can target deeper melanin deposits but are used cautiously to prevent further hyperpigmentation.
• Microneedling: Stimulates collagen and skin renewal, potentially improving PIH, especially when combined with topical agents.

Treatment Duration and Expectations

• Progress is gradual; treatment may take months to years for significant improvement.
• Combination therapy tends to be most effective, especially in stubborn or severe cases.
• Patients should expect slow response and potential recurrence, emphasizing ongoing sun protection.

Summary

PIH is a common, manageable hyperpigmentation disorder caused by inflammation or injury. Effective treatment includes topical depigmenting agents, sunscreens, cosmetic procedures, and lifestyle modifications to minimize inflammation and UV exposure.

Consult with Our Team of Experts Now!

For tailored, dermatologist-guided treatment of PIH, establish a personalized management plan that incorporates topical agents, procedures, and sun protection strategies for optimal results.

References:

1. Bae-Harboe SK, Friedman AJ. Postinflammatory Hyperpigmentation: An Updated Review of Etiology, Epidemiology, and Management. StatPearls. 2024 Nov 24. Available at: https://www.ncbi.nlm.nih.gov/books/NBK559150/​
2. Taylor SC, Karp CL, Nabi J. Treatment of Post-Inflammatory Hyperpigmentation in Skin of Colour: A Systematic Review. J Cutan Med Surg. 2024 Sep 23;28(5):376-385. doi:10.1177/12034754241265716. Available at: https://journals.sagepub.com/doi/10.1177/12034754241265716​
3. Chung J, Kim DH, Hong JW. Inflammatory Response: The Target for Treating Hyperpigmentation during the Repair of a Burn Wound. Front Immunol. 2023 Jan 31;14:1009137. doi:10.3389/fimmu.2023.1009137. Available at: https://www.frontiersin.org/articles/10.3389/fimmu.2023.1009137/full​
4. Grimes PE. Postinflammatory Hyperpigmentation: A Review of the Epidemiology, Clinical Features, and Treatment Options. Am J Clin Dermatol. 2004;5(2):135-142. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2921758/​
5. DermNet NZ. Postinflammatory Hyperpigmentation. 2024 May 22. Available at: https://dermnetnz.org/topics/postinflammatory-hyperpigmentation