Cutis
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Hair pigmentation and graying are important topics for the understanding of the physiology of aging; the differentiation of stem cells; and the mechanisms underlying disease processes such as progeroid syndromes, vitiligo, and hypothyroidism. Although hair graying, or canities, is a common process occurring in people as they age, an unknown percentage of individuals experience premature graying from familial inheritance or pathologic conditions. We review the physiology of hair pigmentation and the mechanism underlying physiologic graying, and we explore the etiology of pathologic causes of premature graying, pathologies associated with premature graying, and the limited available treatment options for hair graying.
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Eruptive xanthomatosis is a papular skin disorder resulting from hyperlipidemia, specifically hypertriglyceridemia. It is characterized by yellowish red papules concentrated on extensor surfaces of the arms and legs. The hyperlipidemia responsible for this disorder can be caused by a primary genetic defect, a secondary disorder, or both. Eruptive xanthomas often rapidly resolve after treatment of the hyperlipidemia has begun.
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Hereditary hemorrhagic telangiectasia (HHT) is an autosomal-dominant disorder. The disease has been formally characterized with epistaxis, cutaneous and mucosal telangiectases, a first-degree relative with HHT, and visceral lesions such as arteriovenous malformations (AVMs). ⋯ Wider recognition of this disorder in recent years has prompted researchers and physicians to recognize milder cases and focus on earlier treatment. This article highlights different treatments used to control epistaxis and screen for other complications associated with HHT.