Rethinking PIH: inflammation may still be active

A new viewpoint in JAMA Dermatology is challenging how clinicians think about postinflammatory hyperpigmentation (PIH). Led by Dr. Jerry K. L. Tan of the University of Western Ontario, the authors argue that PIH — by definition a post-inflammatory condition — is routinely diagnosed while inflammation is still actively present. The result? Clinicians pivot to pigment-targeted therapies and miss the opportunity to continue treating the underlying inflammation driving the discoloration.

The problem is especially pronounced in patients with darker skin tones. Increased epidermal melanin reduces the visibility of erythema (redness), making it far easier to overlook persistent inflammation and prematurely label lesions as PIH. Evidence from colorimetric analyses and histologic studies backs this up — lesions clinically classified as PIH have shown measurable erythema and lymphocytic infiltration, confirming that inflammation hadn't actually resolved.

Key Takeaways

• Reserve the PIH label for cases where inflammation has reasonably resolved; look for subtle clues like itch, scale, or induration
• Anti-inflammatory treatments (e.g., IL-13 inhibitors, topical JAK inhibitors) have been shown to reduce hyperpigmentation, supporting continued inflammation management
• Patients with darker skin tones face higher risk of misdiagnosis due to reduced erythema visibility

Why it matters: Mislabeling active inflammation as PIH leads to incomplete treatment and poorer outcomes — disproportionately affecting patients with darker skin tones who are already at greater risk of persistent hyperpigmentation.