The Skin - Chapter 25 Flashcards
Define and differentiate the disorders of pigmentation.
Freckle (ephelis) – most common pigmented lesion of childhood in lightly pigmented individuals. Will fade and reappear in a cyclic fashion with winter and summer respectively.
Lentigo – a common benign localized hyperplasia of melanocytes occurring at all ages but often in infancy and childhood. Histologically, the most important feature is linear melanocytic hyperplasia.
Melanocytic nevus (pigmented nevus, mole) - common neoplasms caused by acquired activating mutations in components of the Ras signaling pathway.
Dysplastic nevi - may be a precursor for melanoma and are a marker for increased risk of melanoma.
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A lentigo is a small, sharply circumscribed, pigmented macule surrounded by normal-appearing skin.
Melanocytic nevi (typically shortened to “nevi”) are benign neoplasms of melanocytes found within the skin and are commonly referred to as “moles.”
Nevi that have irregular features are commonly termed “dysplastic nevi” or “atypical nevi” (Figures 2-7). The use of the term “dysplastic nevus” is confusing and controversial, since the term is used to describe both lesions with an atypical clinical appearance on the skin as well as those with an atypical appearance microscopically; these are two overlapping but not identical groups
What type of nevi are precursors of malignant melanoma?
Dysplastic nevi
During radial growth, melanomas do, do not have the capacity to metastasize.
Do Not
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Two growth phases, radial and vertical, are commonly identified in cutaneous melanoma. In the radial growth phase, melanoma appears as an irregular plaque; cells may invade the dermis, but do not form a nodule.
The nature and extent of the vertical or radial growth phase determines the biologic behavior of malignant melanoma.
Vertical
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In the vertical growth phase, the lesion develops vertically, forming a true tumour.
What are the important warning signs of melanoma?
Asymmetry
Irregular Borders
Variegated Color
Increasing Diameter
Evolution or change over time, especially if rapid
What are the important warning signs of melanoma?
Asymmetry
Irregular Borders
Variegated Color
Increasing Diameter
Evolution or change over time, especially if rapid
Define and differentiate the four types of benign epithelial tumors of the skin.
Seborrheic Keratosis – These common epidermal tumors occur most frequently in middle aged or older individuals. They arise spontaneously and may be numerous on the trunk, although extremities, head and neck may also be involved. Clinical features – round, flat, coinlike, waxy plaques that vary in diameter from millimeters to several centimeters. They are uniformly tan to dark brown and usually show a velvety to granular surface.
Acanthosis Nigricans – thickened, hyperpigmented skin with a “velvet-like” texture that most commonly appears in the flexural areas. Two types – associated with benign conditions and arises in association with cancers, most commonly gastrointestinal adenocarcinomas.
google: Acanthosis nigricans (this is the black patchy area you see on people who area overweight) typically occurs in people who are obese or have diabetes. More rarely, it can be a warning sign of a cancerous tumor in an internal organ, such as the stomach or liver.
Fibroepithelial polyp – incidental finding in middle-aged and older individuals on the neck, trunk, face, and intertriginous areas as a soft, flesh-colored, bag-like tumor attached to the skin surface by a small, often slender stalk (skin tag).
Epithelial cyst (wen) – formed by the invagination and cystic expansion of the epidermis or a hair follicle. Cysts are filled with keratin and lipid-containing debris derived from sebaceous secretions. Dermal or subcutaneous, well-circumscribed, firm and often movable nodules, when large, may be subject to traumatic rupture, leading to inflammation and pain.
Define and differentiate the most common forms of adnexal tumors of the skin.
Appendage tumors are often clinically nondescript, solitary, or multiple papules and nodules.
Eccrine poroma occurs predominantly on the palms and soles.
Cylindroma – an appendage tumor with ductal differentiation, usually occurs on the forehead and scalp where coalescence of nodules with time may produce a hat-like growth, hence the name turban tumor.
Syringoma – lesions of eccrine differentiation, usually occur as multiple, small, tan papules in the vicinity of the lower eyelids.
Sebaceous adenoma - can be associated with internal malignancy, as in Muir-Torre syndrome
Pilomatricoma - show follicular differentiation
Describe the most common premalignant skin lesion, including the histologic anatomy and pathophysiology.
Actinic keratoses are usually less than 1 cm in diameter; are tan-brown, red, or skin colored, and have a rough, sandpaper-like consistency. Some lesions may produce so much keratin that a “cutaneous horn” develops. Cytologic atypia is seen in the lowermost layers of the epidermis and may be associated with hyperplasia of basal cells or with atrophy that results in thinning of the epidermis. The atypical basal cells usually have pink or reddish cytoplasm due to dyskeratosis. Intercellular bridges are present.
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An actinic keratosis (ak-TIN-ik ker-uh-TOE-sis) is a rough, scaly patch on the skin that develops from years of sun exposure. It’s often found on the face, lips, ears, forearms, scalp, neck or back of the hands.
What is the most important cause of cutaneous squamous cell carcinoma?
DNA damage due to exposure to Ultraviolet (UV) light
The most common invasive cancer in humans is
Basal Cell Carcinoma
Define and differentiate four of the most common tumors of the dermis.
Benign fibrous histiocytoma (dermatofibroma) – formed by benign spindle shaped cells arranged in a well-defined nonencapsulated mass within the mid dermis. Usually seen in adults often occur on the legs of young to middle-aged women.
Dermatofibrosarcoma protuberans – well-differentiated, primary fibrosarcoma of the skin. Slow growing, locally aggressive, rarely metastasize.
question says 4 but answer has only 2/4
Describe mycosis fungoides.
Mycosis fungoides is a T-cell lymphoma that presents in the skin and that may evolve into generalized lymphoma. Most affected individuals have disease that remains localized to the skin for many years; a minority have rapid systemic dissemination. Most commonly afflicts those over 40 years.
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mycosis fungoides and Sézary syndrome are diseases in which lymphocytes (a type of white blood cell) become malignant (cancerous) and affect the skin. Mycosis fungoides and Sézary syndrome are types of cutaneous T-cell lymphoma. A sign of mycosis fungoides is a red rash on the skin.
Define the various types of inflammatory dermatoses of probable hypersensitivity origin.
Urticaria (hives) is a common disorder of the skin characterized by localized mast cell degranulation and resultant dermal microvascular hyperpermeability, culminating in pruritic edematous plaques called wheals. Most commonly the result of antigen-induced release of vasoactive mediators from mast cells.
Acute Eczematous Dermatitis – characterized by red, papulovesicular, oozing and crusted lesions early on that, if persistent, develop into raised, scaling plaques. Antigens at the epidermal surface are taken up by dendritic Langerhans cells, which then migrate by way of dermal lymphatics to draining lymph nodes. Here, antigens now processed by the
Langerhans cell are presented to naïve CD4+ T cells which subsequently develop immunologic memory. On antigen re-exposure, these memory T cells migrate to affected skin where they release cytokines and factors that recruit the numerous inflammatory cells characteristic of eczema.
Erythema Multiforme – uncommon, self-limited disorder that appears to be a hypersensitivity response to certain infections and drugs. Erythema multiforme is characterized by keratinocyte injury mediated by skin-homing CD8+ cytotoxic T lymphocytes. Patients present with an array of “multiform” lesions including macules, papules, vesicles, and bullae as well as the characteristic targetoid lesion consisting of a red macule or papule with a pale, vesicular, or eroded center.
Describe the chronic inflammatory dermatoses.
Psoriasis most frequently affects the skin of the elbows, knees, scalp, lumbosacral areas, intergluteal cleft, and glans penis. The typical lesion is a well demarcated, pink to salmon-colored plaque covered by loosely adherent scales that are characteristically silver-white.
Common chronic inflammatory dermatosis that appears to have an autoimmune base.
Seborrheic Dermatitis - macules and papules on an erythematous-yellow often greasy base, typically in association with extensive scaling and crusting. Fissures may also be present, particularly behind the ears. Classically involves regions with high density of sebaceous glands, such as the scalp, glabella/forehead, external auditory canal, retroauricular area, nasolabial folds and presternal area.
Lichen Planus - pruritic, purple, polygonal, planar papules, and plaques are the presenting signs of this disorder of skin and mucosa (“6 Ps”). Self-limiting and generally resolves spontaneously 1-2 years after onset, often leaving zones of postinflammatory hyperpigmentation
Describe the chronic inflammatory dermatoses.
Psoriasis most frequently affects the skin of the elbows, knees, scalp, lumbosacral areas, intergluteal cleft, and glans penis. The typical lesion is a well demarcated, pink to salmon-colored plaque covered by loosely adherent scales that are characteristically silver-white. Common chronic inflammatory dermatosis that appears to have an autoimmune base.
Seborrheic Dermatitis ( pic in question)- macules and papules on an erythematous-yellow often greasy base, typically in association with extensive scaling and crusting. Fissures may also be present, particularly behind the ears. Classically involves regions with high density of sebaceous glands, such as the scalp, glabella/forehead, external auditory canal, retroauricular area, nasolabial folds and presternal area.
Lichen Planus - pruritic, purple, polygonal, planar papules, and plaques are the presenting signs of this disorder of skin and mucosa (“6 Ps”). Self-limiting and generally resolves spontaneously 1-2 years after onset, often leaving zones of postinflammatory hyperpigmentation.
Define and differentiate the various inflammatory blistering bullous diseases of the skin. What main laboratory test is used to differentiate these diseases?
Pemphigus – blistering disorder caused by autoantibodies that result in dissolution of the intercellular attachments within the epidermis and mucosal epithelium.
Bullous Pemphigoid – Generally affecting elderly individuals, bullous pemphigoid shows a wide range of clinical presentations, with localized to generalized cutaneous lesions and involvement of mucosal surfaces. Lesions are tense bullae filled with clear fluid involving erythematous or normal-appearing skin.
Dermatitis Herpetiformis – characterized by urticaria and grouped vesicles. Affects males more than females, and age at onset is 3rd to 4th decade. Some cases are associated with celiac disease; both the vesicular dermatosis and the enteropathy respond to a gluten-free diet.
Main Laboratory test is direct and indirect immunofluorescence of skin and serum.
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Pemphigus is a disease that causes blistering of the skin and the inside of the mouth, nose, throat, eyes, and genitals.
