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Impairment of the body's immune system results from a variety of causes, including natural aging, ultraviolet radiation, diabetes, malnutrition, cancer, and iatrogenic suppression. While few skin conditions appear solely in immunocompromised individuals, clinical presentations may be morphologically atypical, follow unusual clinical courses, or prove harder to treat than in individuals with intact immunity. This chapter focuses on dermatologic manifestations in immunosuppressed patients without human immunodeficiency virus (HIV) disease, predominantly in those with immunosuppression induced by drugs, conditions surrounding solid organ and bone marrow transplantation, and hematologic malignancy. Skin manifestations of HIV disease are described in Chapter 198. Other chapters cover graft-versus-host disease (see Chapter 28), skin signs associated with primary immunodeficiency disorders (see Chapter 143), and detailed side effects of medications, including corticosteroids, cancer chemotherapeutic agents, immunosuppressants, and cytokines (see Chapters 224, 227, 233, and 234). The salient clinical features particularly associated with immunosuppression are emphasized here.
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While a variety of inflammatory skin diseases and paraneoplastic processes occur in the setting of immunosuppression, infections, and malignancy are most commonly seen and are discussed herein. When approaching an immunocompromised patient, it is helpful to determine the time frame of the immune loss as well as the specific immune defect. This chapter is divided into two major subsections based on this concept: acute immunosuppression and chronic immunosuppression. When patients are acutely immunosuppressed, usually from iatrogenic ablation of the immune system or from acute leukemia, infections occur that are normally controlled by innate immunity, which typically involve neutrophils and macrophages. In chronically immunosuppressed individuals, such as organ transplant patients and those taking corticosteroids on a long-term basis, T-cell function is impaired, and diseases will often be similar to those observed in HIV disease. Thus, it is helpful to understand the underlying immune defects associated with the medical conditions of each patient (Table 29-1), because it helps to focus the history taking and physical examination toward skin manifestations of specific pathogens.
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