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Hands have structures with many unique structural and functional features. As such, they are prone to developing specific dermatologic diseases. Structurally, the palms have a thick keratin layer, a high concentration of sweat glands, Meissner's corpuscles, and other mechanoreceptors. Functionally, we use our hands to explore the world. Therefore, hands are subject to physical injury. Hands are often the first body part to come into contact with objects and substances in our environment. As a result, they are frequently the site of exposure to allergens, irritants, and infectious agents. This concept is central to the transmission of pathogens and development of certain dermatologic conditions such as contact dermatitis. Given their distal location, the neurovascular supply of hands (particularly the digits) can also predispose to neuropathies and ischemic insults. The dorsal hands tend to get more sun exposure than centrally located anatomical structures thereby subjecting them to photodermatoses and actinic damage. Hands may also manifest cutaneous signs of internal disease.
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APPROACH TO DIAGNOSIS
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Skin diseases involving the hands can be broadly placed into the following categories starting with the most common diseases (Table 38-1):
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