Skin problems in immunodeficient patients.

The most important function of the skin besides social communication is active protection against mechanical, chemical and microbial threat. The epidermis has biochemical, physical, immunological and anti-infective properties, and is the most important shield against aggressors. Chronic immunosuppression impairs this cutaneous quality and therefore numerous mucocutaneous complications can occur. The physiological colonization of commensal microbes helps to limit the expansion of pathogenic bacteria, viruses and fungi by a continuous release of antimicrobial peptides from keratinocytes. Genetic or acquired immunodeficiency influences these factors. Malignant neoplastic diseases such as leukemia or lymphomas can also lead to severe immunodeficiency. Drug-induced immunodeficiency is common in organ-transplanted patients with the aim to prevent organ rejection. Such patients with prolonged immunodeficiency often develop atypical presentations of mucocutaneous infections. This is the reason why such patients should be biopsied liberally. In addition to the conventional histology, a part of the biopsy should be used for microbiological cultures. Long-term complications of oncogenic viruses have to be considered leading to epithelial cancers (HPV), Kaposi sarcomas (HHV8), lymphomas (EBV) and Merkel cell tumor (polyomavirus) apart from more known acute infections of the skin. Important mucocutaneous markers of immunosuppression such as oral hairy leukoplakia, oral candidiasis and eczema molluscatum exist. This work reviews the pathophysiology of skin protection and describes typical mucocutaneous problems in immunosuppressed patients.