Postinflammatory hyperpigmentation (PIH) is common in more darkly pigmented persons. It also tends to be a greater cosmetic concern in darkly pigmented individuals than it is in those with lighter skin tones. PIH can occur in any age group or gender. By definition, this form of hyperpigmentation occurs in an area that has sustained prior physical trauma. This trauma may be in the form of a dermatosis such as acne vulgaris or eczema, or it may be mechanical or chemical in nature as might occur following a traumatic cut or chemical burn. Because in most cases PIH resides at a dermal level, injuries that lead to greater disturbance of the dermal-epidermal junction can be expected to yield more profound and persistent PIH. PIH may persist for months to years, and may even be permanent in some cases.

PIH may appear as macules or patches, and depending upon the nature of the insult may be well localized or extensive (Figs. 34-1 and 34-2). Linear PIH may result from trauma that occurred in a linear fashion. PIH mimicking the distribution of dermatoses has also been reported. For example, segmental PIH may occur following a herpes zoster outbreak and linear PIH may result from a dermatosis that follows Blaschko lines. PIH is asymptomatic.