A malignant tumor of melanocytes, most commonly arising from cutaneous melanocytes; can also develop from melanocytes residing elsewhere – e.g. in the uveal tract, retinal pigment epithelium, gastrointestinal mucosa, or leptomeninges. Some cutaneous melanomas (CMs) arise de novo , whereas others arise within precursor lesions (e.g. melanocytic nevi; see Ch. 92 ). Tremendous advances have been made in understanding the molecular pathways and mutations from which…

Benign Pigmented Cutaneous Lesions Other Than Melanocytic Nevi This group of lesions can further be divided into: (1) predominantly epidermal lesions ( Table 92.1 ; Figs 92.1–92.5 ); and (2) dermal melanocytoses ( Table 92.2 ; Figs 92.6 and 92.7 ). Table 92.1 Benign pigmented lesions other than melanocytic nevi (predominantly epidermal lesions). Lesion Major clinical features Ephelid (freckle) Onset in childhood (UVR-induced) and tends to…

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Introduction Variably sized papules or nodules. Cysts can be divided into true cysts with an epithelial lining (histologically and sometimes visible clinically) and false cysts without such a lining. Appreciation of the actual size of the cyst often requires palpation. Different types of cysts often have characteristic anatomic locations and histologic features. Treatment of true cysts (if symptomatic) is primarily surgical. Congenital cysts (e.g. dermoid, branchial…

The entities in this chapter can be further classified according to the algorithm in Fig. 89.1 . Open full size image Fig. 89.1 Simplified classification of benign epidermal proliferations. Although the term solitary lichenoid keratosis is sometimes used, patients may develop multiple lesions, especially those with skin phototypes I or II and significant actinic damage. Entities in italics are not covered. Courtesy, Luis Requena, MD. Common…

Introduction Keratinocyte carcinoma (KC), also referred to as non-melanoma skin cancer (NMSC), is the most frequently observed malignancy in Caucasians. KC typically refers to basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). In individuals with fair skin, ∼75–80% of KCs are BCCs, and up to 25% are SCCs. The two most important risk factors for developing KC are skin phototype (see Appendix) and exposure to…

This chapter covers a range of vascular disorders from livedo reticularis to common vascular ectasias such as venous lakes and telangiectasias. Additional disorders characterized by a proliferation of blood vessels are covered in Chapters 85 (infantile hemangiomas and vascular malformations) and 94 (vascular neoplasms). Livedo Reticularis Blue-violet netlike pattern that reflects an increase in deoxygenated blood within the venous plexus of the skin ( Fig. 87.1…

An ulcer is defined as a wound with loss of the entire epidermis plus dermal tissue, sometimes extending as deep as the subcutis. The most common types of leg ulcers – venous, arterial, and neuropathic – as well as pressure ulcers, lymphedema, and an approach to wound healing are reviewed (see below); additional physical, inflammatory, infectious, metabolic, and neoplastic causes of leg ulcers are outlined in…

Vascular anomalies, which often present at birth or during early infancy, are classified into two groups based on their biologic and clinical behavior: – Vascular tumors , most commonly the infantile hemangioma (IH), that are characterized by endothelial cell proliferation – Vascular malformations that result from abnormal vascular morphogenesis Features that distinguish IHs from vascular malformations are presented in Table 85.1 , and differences in their…

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This chapter focuses primarily on entities in which there is a reduction in collagen and/or elastic tissue within the dermis. They vary from very common skin disorders such as striae to cutaneous manifestations of rare genetic syndromes. Loss of subcutaneous fat, i.e. lipoatrophy, is covered in Chapter 84 , while acrodermatitis chronica atrophicans is covered in Chapter 97 and Ehlers–Danlos syndrome and cutis laxa are covered…

Hypertrophic Scar Firm, initially pink to purple in color then becomes skin-colored to hypopigmented, occasionally hyperpigmented; papule or plaque limited to an excision site or wound ( Figs 81.1 and 81.2 ). Most commonly seen on the trunk and shoulders. Sometimes pruritic. With treatment, can reduce pruritus and height but not width of scar. Rx options include silicone gel sheets, intralesional triamcinolone (initially 5–10 mg/ml), re-excision…

Heritable connective tissue disorders present with a broad range of cutaneous and extracutaneous manifestations. Recognition of characteristic skin findings is often critical to establishing the diagnosis and identifying associated internal involvement, which may include life-threatening cardiovascular disease, e.g. in the vascular type of Ehlers–Danlos syndrome (EDS) and pseudoxanthoma elasticum (PXE). Ehlers–Danlos Syndrome Clinically and genetically heterogeneous group of connective tissue disorders caused by defective function of…

Classically, a group of disorders in which there is transepidermal elimination (“perforation”) of components of the dermis, in particular collagen and/or elastic fibers ( Table 79.1 ). Etiologies are multiple and include inherited as an isolated cutaneous disease or inherited in association with genetic disorders that affect connective tissue (e.g. Ehlers–Danlos syndrome). Most commonly, however, the perforating disorder is acquired and is related to the cutaneous…

When histiocytes form granulomas within the skin, the cutaneous disorders are referred to as granulomatous. This group of disorders is further divided into infectious (e.g. mycobacterial infections, dimorphic fungal infections) and non-infectious (e.g. sarcoidosis, granuloma annulare). This chapter focuses on the latter category. Sarcoidosis Disorder of unknown etiology in which granulomas develop in one or more organs, most commonly the lung, skin, liver, and spleen. Cutaneous…

Key Points Cutaneous xanthomas are due to an accumulation of lipid, primarily within dermal macrophages (foam cells), and they have a characteristic yellow-orange hue. Four major types of xanthomas: eruptive, tuberous, tendinous, and plane. They may be a sign of hyperlipidemia, either primary or secondary, or an underlying monoclonal gammopathy. The type of xanthoma and its anatomic location are clues to the specific lipid abnormality or…

Group of disorders in which the predominant cell type is a Langerhans cell, a mononuclear cell/macrophage, or a dermal dendrocyte. Traditionally, there are two major groups: Langerhans cell histiocytoses and non-Langerhans cell histiocytoses. The V600E variant of BRAF has been detected in both groups. Within these two main groups, the disorders overlap and form a clinicopathologic spectrum. Langerhans Cell Histiocytoses Langerhans cells, which represent the major…

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Cutaneous Injury Due to Heat Exposure Thermal Burns Traumatic injury to the skin caused by an external heat source ( Fig. 74.1 ). The depth of the burn injury depends on the temperature of and the amount of contact time with the heat source as well as the thickness of the affected skin. The burn depth determines the severity and classification of the injury, its potential…