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INTRODUCTION TO CHAPTER
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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 hand to interact with 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 the hands to neuropathies, ischemic insults, and vasculitides. 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 primarily involving the hands can be broadly categorized into inflammatory dermatoses, infections, connective tissue disorders, and photodermatoses (see Table 33-1). Widespread actinic keratoses on the hands are also included in this chapter because they are sometimes misdiagnosed as a "rash." The inflammatory dermatoses are most common and typically present with pruritic papules or plaques. The morphology of tinea manuum depends on its distribution, with annular plaques being more common on the dorsal hand and diffuse fine scale on the palm. Sunlight-induced dermatoses and connective tissue disorders present on the dorsal hands with pink papules and plaques.
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