Abstract Exposure of the skin to UV light leads to both acute, short-term effects (sunburn and tanning) and chronic, long-term effects (photocarcinogenesis and photoaging), all of which are wavelength-dependent. All…

Abstract This chapter reviews the human immunodeficiency virus (HIV) pandemic and the broad spectrum of infectious, inflammatory, and neoplastic skin conditions that may occur in the setting of HIV-induced immune…

Abstract Cutaneous lesions may develop as a result of a variety of environmental insults from heat or cold exposure to water immersion and electricity. Injuries to the skin can also…

Abstract Members of the order Rickettsiales are small, obligately intracellular, Gram-negative bacteria that reside within an arthropod host (tick, flea, louse, or mite) during part of their life cycle. At…

Abstract The diagnosis and management of skin diseases affecting the anogenital region can be more challenging, in part because the typical clinical features observed in glabrous skin are often absent….

Abstract Leukoderma and hypopigmentation refer to lightening of the skin, which is classically due to decreased epidermal melanin (hypomelanosis) but may also result from decreased cutaneous blood supply. Melanocytopenic hypomelanosis…

Abstract Alopecia can reflect the loss of hair follicles, loss of hair shafts, or loss of both. Hair follicle loss may be due to follicular agenesis, dysgenesis, or destruction while…

Abstract Disorders of hyperpigmentation usually result from an increase in melanin production, which is occasionally associated with an increased density of active melanocytes. Skin discoloration may also be caused by…

Abstract Developmental anomalies are congenital disorders that represent either malformations due to faulty embryologic development or disruptions caused by damage to normally developing structures. Midline skin lesions on the nose…

Abstract Hypertrichosis is defined as an excessive growth of hairs anywhere on the body. They are often terminal pigmented hairs but can be vellus or lanugo hairs. Hypertrichosis is frequently…