Itching, technically known as pruritus, is a symptom.  There are many triggers for itching including medications, dry skin, dermatitis, etc.  With chronic itching over a period of time sometimes the skin will react and become more raised, in which case we all this prurigo. When the scratching is particularly severe, the skin may thicken and form a leathery patch or plaque which is referred to as lichen simplex chronicus. Another form of skin reaction to itching is prurigo nodularis where large, itchy nodules appear, most of the time on the outside of the arms or legs.  There are many treatments for itching, including phototherapy, antihistamines, and a variety of topical therapies.  It is also critical for the dermatologist to determine, if possible, the exact cause of itching, particularly in the elderly, as sometimes internal malignancy or disease can be the cause.