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Published on December 29, 2008

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Happy, Successful andHealthyNew Year. : Happy, Successful andHealthyNew Year. Dr. Olga González Rascón Pathologist gonzalez_rascon@yahoo.com ELEMENTARY LESIONS AND INFECTIOUS DISEASES OF THE SKIN : ELEMENTARY LESIONS AND INFECTIOUS DISEASES OF THE SKIN Dr. Olga González Rascon January , 10, 2007 Learning Objectives : Learning Objectives Describe the macroscopic and microscopic changes in frequent lesions of the skin. Define the most frequent forms of infectious skin disease and their pathogenic organisms. WALKING DOWN MEMORY LANE… : WALKING DOWN MEMORY LANE… REMEMBERING FEATURES OF NORMAL SKIN Slide 6: 1. EPIDERMIS Is subdivided into 4 layers: Horny layer (stratum corneum) Granular layer (stratum granulosum) Malpighian layer (prickle-cell layer) Basal layer There is an extra layer found only in palms/soles?lucid layer Slide 7: ...(Continues) Keratinocytes are cells that mature from the basal layer to stratum corneum and their function is related to form a barrier, to secrete PGs, leukotrienes, Ils and induction of Vitamin D by UV rays. Melanocytes (3%) are dendritic cells derived from the neural crest and located into the basal layer, that produce melanin (endogenous screen against UV rays in sunlight). Langerhans cells (4%) can recognize and process Ags and communicate to lymphoid cells. Slide 8: A, The skin is composed of an epidermal layer (e) from which specialized adnexa (hair follicles, h; sweat glands, g; and sebaceous glands, s) descend into the underlying dermis (d). B, This projection of the epidermal layer (e) and underlying superficial dermis demonstrates the progressive upward maturation of basal cells (b) into cornified squamous epithelial cells of the stratum corneum (sc). Melanin-containing dendritic melanocytes (m) (and rare Merkel cells containing neurosecretory granules) and midepidermal dendritic Langerhans cells (lc) are also present. The underlying dermis contains small vessels (v), fibroblasts (f), perivascular mast cells (mc), and dendrocytes (dc), potentially important in dermal immunity and repair. Slide 9: ...(Continues) Merkel cells (<1%) are located also into the basal layer of skin/mucous membranes and function as tactile mechanoreceptor. The basal layer is responsible for epidermal-dermal adherence and probably is a macromolecular filter. It is also a major site for Igs localization. Slide 10: 2. DERMIS Papillary dermis is immediately beneath the epidermis and is formed by collagen fibers. It reacts conjointly with epidermis and superficial capillary-venular bed. Reticular dermis contains most of dermal collagen 3. EPIDERMAL ADNEXA. Includes modified keratinized structures (nails, hair) and sebaceous, eccrine and apocrine glands (axilla, ano-genital areas, nipple and areola) 4. BLOOD VESSELS, NERVES, LYMPHATICS MUSCLES, CELLS (mast cells) SKIN PATHOLOGY : SKIN PATHOLOGY DEFINITIONS OF MACROSCOPIC AND MICROSCOPIC TERMS SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS SKIN PATHOLOGY : SKIN PATHOLOGY RESPONSES OF THE SKIN TO INJURY Clinical lesions – Macroscopic terms Macule Patch Papule Nodule Plaque Vesicle Bulla Blister Pustule Wheal Scale Lichenification Excoriation Onycholysis SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS MACULE A circumscribed lesion of up to 5 mm in diameter, characterized by flatness and usually distinguished from surrounding skin by its coloration. PATCH A circumscribed lesion of more than 5 mm in diameter, characterized by flatness and usually distinguished from surrounding skin by its coloration. Slide 15: Patch Slide 16: Macules and patches SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS PAPULE Elevated dome-shaped or flat-topped lesion 5 mm or less across. PLAQUE Elevated flat-topped lesion usually greater than 5 mm across (may be caused by coalescent papules). Slide 18: Plaque SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS NODULE Elevated lesion with spherical contour greater than 5 mm across. SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS VESICLE Fluid-filled raised lesion 5 mm or less across. SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS BULLA Fluid-filled lesion greater than 5 mm across. SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS BLISTER Common term used for vesicle or bulla. SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS PUSTULE Discrete, pus-filled, raised lesion. SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS WHEAL Itchy, transient, elevated lesion with variable blanching and erythema formed as the result of dermal edema. SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS SCAR Is a hard plaque of dense fibrotic tissue covered by a thin epidermis. A mark of injury from any sort of process. ATROPHY Usually refers to thinning of the epidermis?easily wrinkled and/or shiny surface. It may also apply to dermal and/or subcutaneous tissue, with or without changes in epidermis. SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS ULCER Loss of skin tissue or substance from the surface downward, leaving an uncovered or denuded wound that is slow to heal. EROSION A superficial denudation of the skin, usually implying loss of epidermis. SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS FISSURE Is a vertical splitting/separation of the skin CRUST Dried surface of fluid, often serous (inspissated serum) in nature, with or without tissue debris (same as “scab”) EXCORIATION A scratch mark, often with denudation of the skin to form a small ulcer SKIN PATHOLOGY : SKIN PATHOLOGY MACROSCOPIC TERMS SCALE A thin flake of epithelium (mostly of corneum layer) which is separated from the underlying intact skin. LICHENIFICATION A thickening of the skin and an increase of skin markings, usually seen w/chronic coalescence of papular lesions (atopic eczema). ONYCHOLYSIS Separation of nail plate from nail bed. SKIN PATHOLOGY : SKIN PATHOLOGY MICROSCOPIC TERMS SKIN PATHOLOGY : SKIN PATHOLOGY RESPONSES OF THE SKIN TO INJURY MICROSCOPIC TERMS Hyperkeratosis Parakeratosis Hypergranulosis Acanthosis Papillomatosis Dyskeratosis Acantholysis Spongiosis Hydropic swelling (ballooning) Exocytosis Erosion Ulceration Vacuolization Lentiginous SKIN PATHOLOGY : SKIN PATHOLOGY MICROSCOPIC TERMS HYPERKERATOSIS: Thickening of the stratum corneum, often associated with a qualitiative abnormality of the keratin. PARAKERATOSIS: Modes of keratinization characterized by the retention of the nuclei in the stratum corneum. On mucous membranes, parakeratosis is normal. Slide 42: Hyperkeratosis Slide 43: Parakeratosis SKIN PATHOLOGY : SKIN PATHOLOGY MICROSCOPIC TERMS HYPERGRANULOSIS: Hyperplasia of the statum granulosum, often due to intense rubbing ACANTHOSIS: Diffuse epidermal hyperplasia PAPILLOMATOSIS: Surface elevation caused by hyperplasia and enlargement of contiguous dermal papillae. Slide 45: Acanthosis SKIN PATHOLOGY : SKIN PATHOLOGY MICROSCOPIC TERMS DYSKERATOSIS: Abnormal keratinization occurring prematurely within individual cells or groups of cells below the stratum granulosum. ACANTHOLYSIS: Loss of intercellular connections resulting in loss of cohesion between keratinocytes. SPONGIOSIS: Intercellular edema of the epidermis. Slide 47: Acantholysis Slide 48: Spongiosis SKIN PATHOLOGY : SKIN PATHOLOGY MICROSCOPIC TERMS HYDROPIC SWELLING (BALLOONING) Intracellular edema of keratinocytes, often seen in viral infections. EXOCYTOSIS: Infiltration of the epidermis by inflammatory or circulating blood cells. Slide 50: Hydropic swelling (ballooning) SKIN PATHOLOGY : SKIN PATHOLOGY MICROSCOPIC TERMS VACUOLIZATION: Formation of vacuoles within or adjacent to cells; often refers to basal cell-basement membrane zone area. LENTIGINOUS: Referring to a linear pattern of melanocyte proliferation within the epidermal basal cell layer. Lentiginous melanocytic hyperplasia can occur as a reactive change or as part of a neoplasm of melanocytes. BONUS MATERIAL : BONUS MATERIAL SKIN PATHOLOGYBonus Material : SKIN PATHOLOGYBonus Material SKIN RESPONSE IN SYSTEMIC DISEASES. HYPERPIGMENTATION -Addison´s disease -Hemochromatosis -Heavy metal poisoning (As,Ag) -Chronic renal failure -Chronic liver disease SKIN PATHOLOGYBonus Material : SKIN PATHOLOGYBonus Material SKIN RESPONSE IN SYSTEMIC DISEASES HYPOPIGMENTATION -Albinism -Chediak-Higashi syndrome -Hypopituitarism SKIN PATHOLOGY – Bonus Material : SKIN PATHOLOGY – Bonus Material SKIN RESPONSE IN SYSTEMIC... DARK SPOTS -Peutz-Jegher´s syndrome -Albright´s syndrome -Neurofibromatosis ORANGE-YELLOW PIGMENT -Jaundice -Hypervitaminosis A, etc. PRURITUS -Chronic renal failure -Obstructive jaundice -Hodgkin’s disease SKIN PATHOLOGYBonus Material : SKIN PATHOLOGYBonus Material SKIN RESPONSE IN SYSTEMIC... HEMORRHAGIC PETECHIAE -Bacterial endocarditis -Scurvy -Thrombocytopenic purpura -Septicemia -Vasculitis BRUISES -Amyloidosis -Leukemia -Bacteremia -Scurvy -Cushing´s syndrome SKIN PATHOLOGYBonus Material : SKIN PATHOLOGYBonus Material SKIN RESPONSE IN SYSTEMIC... TELANGIECTASIA -Chronic liver failure -Osler-Weber-Rendu syndrome HIRSUTISM -Cushing’s syndrome -Increased levels of androgens HAIR LOSS -Hypothyroidism -SLE SKIN PATHOLOGYBonus Material : SKIN PATHOLOGYBonus Material SKIN RESPONSE IN SYSTEMIC... HYPERKERATOSIS -Hypervitaminosis A -Scurvy ACANTHOSIS NIGRICANS -Mostly abdominal carcinomas (stomach) -Also: some lung and breast carcinomas DERMATITIS -Hypervitaminosis A -Parkinson’s diease -Pellagra END OF BONUS MATERIAL : END OF BONUS MATERIAL SKIN PATHOLOGY : SKIN PATHOLOGY INFECTIOUS DISEASES AND INFESTATION INFECTION AND INFESTATION : INFECTION AND INFESTATION Verrucae (warts) Common lesions of children and adolescents, may be encountered at any age. Caused by human papillomaviruses. Generally self-limited, regressing spontaneously. Verruca vulgaris Verruca plana Verruca plantaris Verruca palmaris Condyloma acuminatum (venereal wart) … (Continues) : … (Continues) …(Continues) Pathogenesis: Anogenital warts are caused predominantly by HPV types 6 and 11 (HPV type 16 shows some degree of dysplasia, associated with in situ squamous cell carcinoma of the genitalia). HPV types 5 and 8 have been detected also. …(Continues) : …(Continues) Molluscum Contagiosum Is a common self-limited viral disease of the skin caused by a poxvirus (largest pathogenic poxvirus in humans). Clinically, multiple lesions may occur on the skin and mucous membranes (trunk and anogenital areas). SKIN PATHOLOGY : SKIN PATHOLOGY VIRUSES Herpes simplex I (oral blisters) and herpes simplex II (genital blisters). Varicella (blisters on trunk?periphery) …(Continues) : …(Continues) Impetigo Common superficial bacterial infection of the skin. Pathogenesis: Beta-hemolytic streptococci and Staphylococcus aureus (most of the cases nowadays). …(Continues) : …(Continues) Superficial fungal infections Caused primarily by dermatophytes. Tinea capitis Tinea barbae Tinea corporis Tinea cruris Tinea pedis (athlete’s foot) Spread to or primary infection of the nails is referred to as onychomycosis. …(Continues) : …(Continues) …(Continues) Tinea versicolor (Malassezia furfur), a yeast. …(Continues) : …(Continues) Arthropod bites, stings, and infestations Arachnida (spiders, scorpions, ticks, and mites) Insecta (lice, bedbugs, bees, wasps, fleas, flies, and mosquitoes) Chilopoda (centipedes). …(Continues) : …(Continues) …(Continues) Arthropods can produce lesions: 1. By direct irritant effects of insesct parts or secretions. 2. By immediate or delayed hypersensitivity responses (including an anaphylactic reaction) 3. By specific effects of venoms (e.g. black widow spider venom produces severe cramps and excruciating pain, the brown recluse spider venom contains potent enzymes that produce tissue necrosis) 4. By serving as vectors for secondary invaders, such as viruses, bacteria, rickettsiae, and parasites. …(Continues) : …(Continues) …(Continues) Ixodes dammini, a tick vector for the spirochete that causes Lyme disease. Pediculosis, caused by the head louse, crab louse, and body louse. Scabies, caused by the mite Sarcoptes scabei. THANK YOU! : THANK YOU! Dr. Olga González Rascón CREDITS : CREDITS Books: Robbins and Cotran’s Pathologic Basis of Disease Images: Department of Pathology collections (special thanks to Dr. Martinez, Dr. Montiel), Dermatology: U of Iowa, Elsevier - PBD, and various public Internet sources.

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