Hyperpigmentation in darker skin may indicate active inflammation

Clinical takeaway: Do not assume hyperpigmentation means inflammation has resolved. Check for itch, tenderness, scale, induration, recurrence, or lesion evolution before choosing pigment-only treatment.

A dark patch after acne or eczema can look like the final mark of a flare that has run its course. In people with darker skin tones, inflammation may be difficult to recognize visually, making it easy to assume it has resolved when it may still be active. The label post-inflammatory hyperpigmentation reinforces a simple sequence in which inflammation ends and discoloration remains.

In a prospective study of 29 participants with Fitzpatrick skin types II to VI, ranging from skin that usually burns and tans minimally to deeply pigmented skin that rarely or never burns, acne lesions clinically classified as post-inflammatory hyperpigmentation remained dark over 35 days. Objective color testing also detected persistent erythema, or redness caused by inflammation, even as clinician-rated erythema declined. In a related experimental model, biopsies taken 28 days after inflammation was induced showed persistent lymphocytic infiltration around follicles and blood vessels.

The authors argue that the post-inflammatory label can encourage premature diagnostic closure, particularly when erythema is not visually prominent. Itch, tenderness, subtle induration or scale, and recurrence or evolution in the same distribution may point to inflammation that remains active.

Corresponding author Jerry Tan, MD, of the Department of Medicine at Western University, and colleagues wrote of post-inflammatory hyperpigmentation (PIH): “The clinical implication is not that all hyperpigmentation reflects ongoing inflammation, or that the term PIH must be abandoned in every context. Rather, clinicians should reserve the term PIH for situations in which inflammatory activity has reasonably resolved and avoid using it when ongoing inflammation is present or strongly suspected.”

Source: Tan, et al (2026 Aug 5). JAMA Dermatol. Is postinflammatory hyperpigmentation truly “post” in people with darker skin tones?