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Vascular Neoplasms and Neoplastic-Like Proliferations

Introduction In this chapter we use the term neoplasm synonymously with tumor in a general, albeit imperfect , sense, consistent with its common usage: an abnormal proliferation (“new growth”) of cells that appears to be relatively autonomous (i.e. not reactive) . Of note, common infantile hemangiomas are discussed separately (see Ch. 103 ) as are telangiectatic lesions (see Ch. 106 ) and vascular malformations (see Ch.…

Melanoma

Key features ▪ Melanoma represents a malignant tumor that arises from melanocytes, and, due to its metastatic potential, leads to >90% of skin cancer deaths ▪ The incidence rates of melanoma have increased over the past four decades by five- to seven-fold, whereas mortality rates began to stabilize in the early 1990s ▪ In situ and early invasive cutaneous melanoma can be subtle in appearance but…

Benign Melanocytic Neoplasms

Ephelides Synonym ▪ Freckles Key features ▪ Small, well-circumscribed, pigmented macules found only on sun-exposed skin of individuals with fair skin Epidemiology and Pathogenesis Ephelides are common in individuals with blond or red hair . They are not present at birth, but usually begin to appear during the first 3 years of life. The hyperpigmentation in ephelides is the result of increased sun-induced melanogenesis and transport…

Adnexal Neoplasms

Key features ■ Terminology and classification of adnexal tumors has varied considerably according to different authorities ■ Adnexal neoplasms can differentiate toward the folliculosebaceous-apocrine unit or the eccrine apparatus ■ As a reflection of joint ontogeny, tumors often exhibit combinations of follicular, sebaceous and apocrine differentiation ■ Many adnexal tumors historically classified as eccrine are probably apocrine The nosology of adnexal neoplasms has been confused for…

Cysts

Key features ▪ Multiple types of cutaneous cysts have been described ▪ Cutaneous cysts present as circumscribed dermal or subcutaneous papules or nodules ▪ Histologic features of the cyst lining and the anatomic location determine the type of cyst ▪ Cysts may be lined by either stratified squamous epithelium or non-stratified squamous epithelium; cystic structures without an epithelial lining are better classified as pseudocysts ▪ Treatment…

Benign Epidermal Tumors and Proliferations

The majority of entities in this chapter can be further classified according to the algorithm in Fig. 109.1 . Open full size image Fig. 109.1 Further 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. Solar Lentigo Synonyms ▪ Lentigo senilis ▪ Liver spot…

Actinic Keratosis, Basal Cell Carcinoma, and Squamous Cell Carcinoma

Synonyms ▪ Solar keratosis and senile keratosis are non-preferred synonyms for actinic keratosis (solar keratosis is abbreviated to SK, causing confusion with seborrheic keratosis) ▪ Bowen disease: squamous cell carcinoma in situ , intraepidermal carcinoma ▪ Basal cell epithelioma and rodent ulcer are antiquated synonyms for basal cell carcinoma ▪ Basal cell nevus syndrome: nevoid basal cell carcinoma syndrome, Gorlin syndrome, Gorlin–Goltz syndrome Key features ▪…

Principles of Tumor Biology and Pathogenesis of BCCs and SCCs

Key features ▪ Oncogenes act in a dominant fashion and gain-of-function results in increased cellular proliferation ▪ Tumor suppressor genes act in a recessive fashion and loss of normal function results in uncontrolled growth ▪ TP53 , the gene that encodes p53, is the single most frequently mutated gene in human cancer; p53 controls signaling pathways involved in cell division and apoptosis ▪ Mutations in either…

Other Vascular Disorders

Introduction This chapter will cover several disorders of the skin vasculature, including livedo reticularis, flushing and erythromelalgia, as well as vascular ectasias such as telangiectasias and venous lakes. Some of the diseases described here are important skin signs of systemic disease, while others are incidental findings. Additional disorders of blood vessels are covered elsewhere, e.g. infantile hemangiomas ( Ch. 103 ), vascular malformations ( Ch. 104…

Ulcers

Synonyms ■ Ulcer – wound, sore ■ Venous ulcer – ulcer due to venous insufficiency/venous hypertension ■ Arterial ulcer – ulcer due to atherosclerosis ■ Neuropathic ulcer – mal perforans ■ Livedoid vasculopathy – atrophie blanche, livedoid vasculitis ■ Pressure ulcer – decubitus ulcer, pressure sore, bed sore Key features ■ The history should include onset, course, symptoms, exacerbating and alleviating factors, past medical history, family…

Vascular Malformations

Synonyms ▪ Vascular birthmarks; mature angiomas [misnomer]; angiodysplasias ▪ Capillary malformation (CM): port-wine stain, nevus flammeus ▪ Venous malformation (VM): cavernous angioma [misnomer], cavernous hemangioma [misnomer], phlebectasia ▪ Lymphatic malformation (LM): lymphangioma, lymphangioma circumscriptum, lymphangioma simplex, cystic hygroma, cavernous lymphangioma ▪ Arteriovenous malformation (AVM): cirsoid aneurysm, cirsoid hemangioma Key features ▪ Although both were once called “angiomas”, vascular malformations differ from the vascular tumors seen in…

Infantile Hemangiomas

Synonyms ▪ Hemangioma of infancy ▪ Hemangioma Key features ▪ The most common benign soft tissue tumor of infancy ▪ Demonstrate a typical growth pattern characterized by early proliferation followed by gradual, spontaneous involution ▪ Distinct histopathologic and immunohistochemical features that differentiate them from other vascular anomalies in children ▪ May be associated with extracutaneous findings when occurring at certain anatomic sites, e.g. the face, neck,…

Vascular Biology

Key features ▪ Cutaneous blood vessels and lymphatic vessels play important roles in skin inflammation and tumor progression ▪ Vascular endothelial growth factor-A (VEGF-A) and placental growth factor (PlGF) are major skin angiogenesis factors ▪ Expression of VEGF and PlGF by keratinocytes is upregulated in psoriasis, healing wounds, and cutaneous squamous cell carcinomas ▪ VEGF-C and VEGF-D induce skin lymphangiogenesis via interaction with VEGF receptor-3 on…

Lipodystrophies

Synonyms ▪ Lipodystrophy: lipoatrophy, lipohypertrophy Key features ▪ Lipodystrophies are inherited or acquired disorders characterized by a paucity or complete absence of fat that may be generalized, partial or localized; lipohypertrophy may accompany the lipoatrophy ▪ Though the terms lipodystrophy and lipoatrophy are often used interchangeably, lipoatrophy should be used specifically for selective loss of fat, with lipodystrophy implying a redistribution of fat, in part due…

Panniculitis

Introduction Panniculitis is a diagnostically challenging arena for dermatologists and pathologists. Terminology is difficult, partly because various names have been applied to the same disorder (e.g. nodular vasculitis and erythema induratum), and partly because new discoveries have resulted in the introduction of new terms and the abandonment of others. From a clinical standpoint, many forms of panniculitis with diverse etiologies closely resemble one another, presenting as…

Atrophies of Connective Tissue

Atrophies of the skin that are due to a diminution or loss of collagen and/or elastic fibers are discussed in this chapter. The areas of involvement can be quite large, as in mid-dermal elastolysis, or punctate, as in follicular atrophoderma. In most disorders, the underlying pathogenesis remains to be discovered. Mid-Dermal Elastolysis Key features ▪ Uncommon disorder with areas of fine wrinkling ▪ Usually affects Caucasian…

Dermal Hypertrophies

This chapter will discuss disorders in which there are increased amounts of collagen within the skin, followed by those with increased elastin. Hypertrophic Scars and Keloids Key features ▪ Conventional scars are preceded by injury, immediate in onset, flat, and asymptomatic ▪ Hypertrophic scars are raised and confined to the wound margin. Sometimes they improve spontaneously and tend to have a good response to treatment ▪…

Heritable Disorders of Connective Tissue

Key features ■ Heritable connective tissue disorders with skin involvement comprise a phenotypically diverse group of conditions ■ Recognition of characteristic skin findings is often critical to establishing the diagnosis and identifying associated internal involvement, which may include life-threatening cardiovascular disease as in vascular Ehlers–Danlos syndrome and pseudoxanthoma elasticum ■ Heritable connective tissue disorders can result from mutations in genes encoding structural extracellular matrix (ECM) proteins…

Perforating Diseases

Synonyms ▪ Hyperkeratosis follicularis et parafollicularis in cutem penetrans: Kyrle disease ▪ Acquired perforating dermatosis: acquired reactive perforating collagenosis, acquired reactive perforating dermatosis, perforating disorder of uremia Key features ▪ Group of disorders with transepidermal elimination of collagen, elastic tissue, or necrotic dermal connective tissue ▪ Papules or nodules with keratotic plugs ▪ Elastosis perforans serpiginosa is associated with genetic diseases or penicillamine administration and involves…

Biology of the Extracellular Matrix

Key features ▪ Extracellular matrices (ECMs) represent specifically organized networks of collagens, elastin, glycoproteins, and proteoglycans that have distinct structural roles and specific functional properties in all tissues ▪ ECMs are biologically active, interact with cells, and regulate their functions during development, regeneration, and normal tissue turnover ▪ Mutations in ECM genes cause a broad spectrum of human diseases, from Ehlers–Danlos syndrome to epidermolysis bullosa, and…