sentences:  Keloid scars from acne occur more often in men and people with darker skin, and usually occur on the trunk of the body.After an inflamed nodular acne lesion resolves, it is common for the skin to darken in that area, which is known as postinflammatory hyperpigmentation (PIH).The inflammation stimulates specialized pigment-producing skin cells (known as melanocytes) to produce more melanin pigment, which leads to the skin's darkened appearance.