Post-inflammatory hyperpigmentation, or PIH, is the medical term given to discoloration of the skin that follows an inflammatory wound. It is the skin's natural response to inflammation.
PIH looks like flat areas of discoloration on the skin (macules). The can range in color -- pink, red, purple, brown or black -- depending on your skin tone and depth of the discoloration.
You can identify post-inflammatory hyperpigmentation by carefully examining the skin. PIH macules can be a range of colors, however, the skin will not be pitted or depressed. It may look like a discolored freckle on the skin, or even a larger, splotchy discoloration of the skin. The macules themselves may look shiny, or like "new skin."
PIH is very common among acne sufferers. It can occur in all skin types, although it is more common in darker skin tones. It affects both men and women equally. Luckily, PIH is not a true scar.