(4) Skin Disorders
What happens as we age?
Many histological changes occur with aging and photoaging. Variation in cell size, shape, and staining results in epidermal dyscrasia of photoaged skin. Melanocytes decline, and Langerhans’ cells (intradermal macrophages) decrease in density.
The dermis becomes relatively acellular, avascular, and less dense, and the loss of functional elastic tissue results in wrinkles.
The nerves, microcirculation, and sweat glands undergo a gradual decline, predisposing them to decreased thermoregulation and sensitivity to burning. Nails undergo a slow decline in growth, with thinning of the nail plate, longitudinal ridging, and splitting. The subcutaneous fat layer atrophies on the cheeks and distal extremities but hypertrophies on the waist of men and thighs of women
Aging Skin
Epidermal Changes
• Melanocytes
Approximately 15% decline per decade
Density doubles on sun-exposed skin
Increased lentigines
• Langerhans cells
Decreased density
Decreased responsiveness
Dermal Changes
Decreased collagen—1% annual decline, altered fibers
Decreased density
Progressive loss of elastic tissue in the papillary dermis
Skin Changes in Aging
Loss of Elasticity and Thinning of the Skin
Clinical results-xerosis, laxity, wrinkling, uneven pigmentation, easy tearing, traumatic pupura, neoplasia
Photoaging
Clinical results-actinic keratoses, fine and coarse wrinkling, telangiectasia, blotchiness and pigmentary changes, elastotic skin with giant comedones
Many skin changes occur during the aging process, including decreased elasticity, decreased skin surface lipids and hydration, and decreased skin density and responsiveness. These skin changes can be divided into intrinsic skin changes and extrinsic changes, as explained previously.
Although intrinsic changes usually begin in our 20s, the signs are typically not visible for decades. These include the following:
• Fine wrinkles
• Thin and transparent skin
• A loss of underlying fat, leading to hollowed cheeks and eye sockets, as well as noticeable loss of firmness on the hands and neck
• An inability to sweat sufficiently to cool the skin
• Bones that shrink away from the skin because of bone loss, which causes sagging skin
• Dry skin that may itch
• Graying hair that eventually turns white
• Hair loss
• Unwanted hair
• A nail plate that thins, the half moons that disappear, and ridges that develop
Terms:
Photoaging - The damaging of skin due to sunlight exposure.
Langerhans’ cells - A type of dendritic immune cell found in high concentrations in the epidermis.