The skin of elderly persons is thinner and drier and possesses a greater number of growths than the skin of young and middle-aged persons. These physical changes are accompanied by other changes in lifestyle and psychological state that appear to make elderly persons more prone to rub, scratch, and pick at their skin.
Such activities result in a variety of dermatoses and evoke various reactive changes in the skin that will be reviewed in this 2-part series. Here I discuss postinflammatory pigmentary alteration (PIPA), amyloidosis, lichen simplex chronicus (LSC), and prurigo nodularis. In a coming issue (August 2010), I will address neurotic excoriations, perforating disease, chondrodermatitis nodularis chronica helicis, hyperkeratosis of the foot, calluses and corns, and intertrigo.
PIGMENTARY ALTERATION CAUSED BY SCRATCHING
PIPA is caused by 3 interrelated mechanisms that operate in whole or in part:
•Epidermal melanosis.
•Dermal melanosis.
•Pigmentary incompetence.
Among the most common causes of PIPA in elderly persons are rubbing and scratching of the skin 
The epidermal inflammatory response (ie, dermatitis) results in the release of inflammatory mediators that alter the activity of both immune cells and melanocytes, which increase pigment production and the transfer to and fixation of melanin in keratinocytes, all of which manifest as epidermal hypermelanosis. Dermal melanosis occurs when inflammation disrupts the basal cell layer, releasing melanin pigment, which is subsequently trapped by papillary dermal macrophages; this effect is also known as pigmentary incontinence. Dermal melanosis can be related to the localization of melanocytes in the dermis, which appears blue because of the Tyndall effect (the preferential absorption of long light wavelengths by melanin and the scattering of shorter wavelengths, representing the blue end of the spectrum, by collagen(Drug information on collagen) bundles).1
If the cause of PIPA is unclear, a biopsy is helpful in excluding other underlying causes of hyperpigmentation. Staining of the biopsy specimen with Fontana-Masson silver stain for melanin enables localization of the melanin in the epidermis and/or the dermis. The color of the lesions ranges from light brown to black, with a lighter brown appearance if the pigment is within the epidermis (ie, epidermal melanosis) and a darker gray appearance if lesions contain dermal melanin (ie, dermal melanosis).
Treatment of PIPA is difficult. When it appears on the face, combination therapies of a retinoid, hydroquinone(Drug information on hydroquinone), and a mild corticosteroid can be helpful.2 The best therapy for PIPA on the body is the tincture of time because the pigmentary alteration tends to lessen over time and responds poorly to treatment.
