Dermatology Primer

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Dermatology Primer. A resident physician’s perspective. Objectives. Review the basic anatomy of the integumentary system Review how to approach the dermatologic examination Recognize basic skin lesions and patterns Review of some dermatologic manifestations of systemic disease.
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Dermatology PrimerA resident physician’s perspectiveObjectives
  • Review the basic anatomy of the integumentary system
  • Review how to approach the dermatologic examination
  • Recognize basic skin lesions and patterns
  • Review of some dermatologic manifestations of systemic disease
  • Anatomy of the skinAnatomy of the skin
  • A.Epidermis (external skin surface)
  • 1.Keratinised squamous epithelium
  • 2.Thickness
  • a.Eyelids: 0.05 mm
  • b.Palms and soles: 1.5 mm
  • B.Dermis (supports epidermis)
  • 1.Thick, dense, fibroelastic connective tissue
  • 2.Highly vascularized
  • 3.Contains sensory receptors
  • C.Hypodermis (Subcutaneous layer)
  • 1.Loose connective tissue with adipose tissue
  • Anatomy of the skin
  • A.StratumCorneum (Cornified Layer)
  • 1.Outermost layer of epidermis
  • 2.Composed mostly of keratin (fibrous protein)
  • 3.Cells desquamated (27 days after production)
  • B.StratumLucidum (present only in very thick skin)
  • C.StratumGranulosum (Granular Layer)
  • 1.Darker layer with intracellular granules
  • 2.Produces keratin
  • D.StratumSpinosum (Prickle Cell Layer)
  • 1.Composed of keratinocytes
  • 2.Cells produced by basal layer and growing
  • 3.Keratin production starts
  • E.StratumGerminativum (Stratum Basale, Basal Cell Layer)
  • 1.Innermost layer of epidermis
  • 2.Cells are produced here in the germinal layer
  • 3.Forms the prickle cells in the layer above
  • Anatomy of the skin
  • A.Hair Follicle
  • 1.Hair producing unit based in Hypodermis
  • 2.Cylinder that ascends through surface epithelium
  • 3.Hair held within center of follicle's cylinder
  • 4.Entire follicle encased in connective tissue
  • B.Sweat Gland
  • 1. Merocrine and apocrine
  • C.Sebaceous Gland
  • 1. Secrete sebum
  • D.Melanocyte
  • 1. Melanin (brown pigment) produced within melanosome
  • E.Merkel's Cell
  • F.Langerhans Cells (in Prickle Layer)
  • 1.Dendritic histiocytic cells
  • 2.Intercept antigenic signal and pass to lymphoid cells
  • G.Desmosome (Macula adherens)
  • 1.Intercellular bridge that attaches epidermal cells
  • 2.Small dense Plaque with protruding tonofilaments
  • Skin functions
  • A.Sensation (largest sensory organ in the body)
  • B.Protection
  • 1.Prevents dehydration
  • 2.Prevents infection
  • 3.Physical barrier to injury
  • 4.Protects against ultraviolet light injury (Melanin)
  • C.Thermoregulation
  • 1.Insulation (hair and adipose tissue)
  • 2.Heat dissipation
  • a.Sweat evaporation
  • b.Increased blood flow
  • D.Metabolic
  • 1.Energy storage of Triglycerides in adipose tissue
  • 2.Vitamin D synthesis
  • Approach to derm patient
  • Use magnification
  • Feel lightly
  • Palpate deeply
  • Distribution
  • Local patterns - groups, rings, lines
  • Look at nails, hair, mucus membranes, hands, feet
  • nail pitting for psoriasis
  • scalp may be clue to seborrhea elsewhere
  • lichen planus with a white lacy pattern in the mouth
  • fungal infection on the feet and hand
  • Approach to derm patient
  • Think pathophysiology
  • Infections
  • Inflammatory Processes - dermatitis, seborrhea
  • Acne and related disorders
  • Immunologic
  • Benign and premalignant growths
  • Malignancies
  • Morphology of lesions
  • An extensive language has been developed to standardize the description of skin lesions, including
  • Primary morphology (lesion type)
  • Secondary morphology (configuration)
  • Texture
  • Distribution
  • Color
  • Basic skin lesions
  • Macule
  • A macule is a change in the color of the skin. It is flat; if you were to close your eyes and run your fingers over the surface of a purely macular lesion, you could not detect it. A macule greater than 1 cm. may be referred to as a patch.
  • Basic skin lesions
  • Papule
  • A papule is a solid raised lesion that has distinct borders and is less than 1 cm in diameter. Papules may have a variety of shapes in profile (domed, flat-topped, umbilicated) and may be associated with secondary features such as crusts or scales.
  • Basic skin lesions
  • Nodule
  • A nodule is a raised solid lesion more than 1 cm. and may be in the epidermis, dermis, or subcutaneous tissue.
  • Basic skin lesions
  • Plaque
  • A plaque is a solid, raised, flat-topped lesion greater than 1 cm. in diameter. It is analogous to the geological formation, the plateau.
  • Basic skin lesions
  • Vesicles
  • Vesicles are raised lesions less than 1 cm. in diameter that are filled with clear fluid.
  • Basic skin lesions
  • Wheal
  • A wheal is an area of edema in the upper epidermis.
  • Basic skin lesions
  • Telangiectasia
  • Telangiectasia are the permanent dilatation of superficial blood vessels in the skin and may occur as isolated phenomena or as part of a generalized disorder, such as ataxia telangiectasia.
  • Secondary morphology (pattern)
  • Configuration is the shape of single lesions and the arrangement of clusters of lesions.
  • Linear lesions take on the shape of a straight line and are suggestive of some forms of contact dermatitis, linear epidermal nevi, and lichen striatus.
  • Annular lesions are rings with central clearing. Examples include granuloma annulare, some drug eruptions, some dermatophyte infections (eg, ringworm), and secondary syphilis.
  • Secondary morphology (pattern)
  • Nummular lesions are circular or coin-shaped; an example is nummular eczema.
  • Target (bull's-eye or iris) lesions appear as rings with central duskiness and are classic for erythema multiforme.
  • Serpiginous lesions have linear, branched, and curving elements. Examples include some fungal and parasitic infections (eg, cutaneous larva migrans).
  • Reticulated lesions have a lacy or networked pattern. Examples include cutis marmorata and livedo reticularis.
  • Secondary morphology (pattern)
  • Herpetiform describes grouped papules or vesicles arranged like those of a herpes simplex infection.
  • Zosteriform describes lesions clustered in a dermatomal distribution similar to herpes zoster.
  • Dermatologic manifestations of systemic disease
  • Many systemic diseases have skin changes associated with them
  • In some cases, the cutaneous manifestations may be the first or most obvious sign
  • Pulmonary
  • Sarcoidosis
  • The skin is involved in 15% to 35% of cases
  • Lesions may present as:
  • Lupus pernio (red swelling of the nose)
  • Translucent papules around the eyes and nose
  • Annular lesions with central atrophy
  • Nodules on the trunk and extremities
  • Scar sarcoid
  • Erythema nodosummay be associated with acute sarcoidosis
  • Granulomatosis
  • Skin lesions in up to 60% of cases
  • Lesions include purpura, nodules and infarcts
  • Cardiovascular
  • Pseudoxanthoma elasticum
  • Papaules in distribution
  • Degeneration of elastic fibres
  • Associated with stroke, myocardial infarction, peripheral vascular disease, GI hemorrhage
  • Ehlers-Danlos syndrome
  • Skin hyperextensibility
  • Associated with angina, peripheral vascular disease, GI hemorrhage
  • Erythema marginatum
  • Associated with acute rheumatic fever
  • Gastrointestinal and Nephrologic
  • Osler-Weber-Rendu syndrome
  • Nosebleeds and gastrointestinal bleeds
  • Cutaneous and mucosal telangiectasias
  • Dermatitis herpetiformis
  • Immune-mediated bullous disease
  • Associated with gluten-sensitive enteropathy
  • Uremic pruritus
  • Associated with end-stage renal disease
  • Neurocutaneous
  • Ataxia-telangiectasia
  • Cutaneous and ocular telangiectasia, cerebellar ataxia, choreoathetosis, recurrent lung infections
  • Tuberous sclerosis
  • Hyperpigmented macules, fibromas, epilepsy
  • Sturge-Weber-Dimitri syndrome
  • Capillary angioma in distribution of the upper or middle branch of the trigeminal nerve
  • Rheumatologic
  • Psoriatric arthritis
  • Occurs in 5% to 8% of patients with psoriasis
  • Reiter syndrome
  • Triad of urethritis, conjunctivitis, and arthritis
  • Erythema migrans
  • Annular plaque presentation of Lyme disease, a spirochete infection following an infected tick bite
  • Lupus erythematosus
  • Cutaneous abnormalities occur in 80% of patients
  • Endocrinologic
  • Diabetes
  • Necrobiosis lipoidica diabeticorum
  • Yellow brown atrophic telangiectatic plaques on shins
  • Granuloma annulare
  • Papular eruption possibly associated with diabetes
  • Pretibial myxedema
  • Associated with Graves disease
  • Nail clues to Systemic diseaseClubbing Inflammatory bowel disease, pulmonary malignancy, asbestosis, chronic bronchitis, COPD, cirrhosis, congenital heart disease, endocarditis, atrioventricular malformations, fistulasKoilonychiaIron deficiency anemia, hemochromatosis, Raynaud’s disease, SLE, trauma, nail-patella syndromeOnycholysisPsoriasis, infection, hyperthyroidism, sarcoidosis, trauma, amyloidosis, connective tissue disordersNail clues to Systemic diseasePittingPsoriasis, Reiter’s syndrome, incontinentia pigmenti, alopecia areataBeau’s linesAny severe systemic illness that disrupts nail growth, Raynaud’s disease, pemphigus, traumaYellow nailLymphedema, pleural effusion, immunodeficiency, bronchiectasis, sinusitis, rheumatoid arthritis, nephrotic syndrome, thyroiditis, tuberculosis, Raynaud’s diseaseNail clues to Systemic diseaseTerry’s (white) nails Hepatic failure, cirrhosis, diabetes mellitus, CHF, hyperthyroidism, malnutritionAzure lunula Hepatolenticular degeneration (Wilson’s disease), silver poisoning, quinacrine therapyHalf-and-half nails Specific for renal failureMuehrcke’s lines Specific for hypoalbuminemiaMees’ lines Arsenic poisoning, Hodgkin’s disease, CHF, leprosy, malaria, chemotherapy, carbon monoxide poisoning, other systemic insultsNail clues to Systemic diseaseDark longitudinal streaks Melanoma, benign nevus, chemical staining, normal variant in darkly pigmented peopleLongitudinal striations Alopecia areata, vitiligo, atopic dermatitis, psoriasisSplinter hemorrhage Subacute bacterial endocarditis, SLE, rheumatoid arthritis, antiphospholipid syndrome, peptic ulcer disease, malignancies, oral contraceptive use, pregnancy, psoriasis, traumaTelangiectasia Rheumatoid arthritis, SLE, dermatomyositis, scleroderma Questions?
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