BASICS OF DERMATOLOGY DR MALCOLM PINTO ASSISTANT PROFESSOR
BASICS OF DERMATOLOGY DR. MALCOLM PINTO ASSISTANT PROFESSOR YENEPOYA MEDICAL COLLEGE YENEPOYA UNIVERSITY
Learning objectives � Layers of the skin � Types of skin lesions � Functions of the skin � Basics in history taking
Structure of Skin
Layers of the skin
Diagnosis of disease in dermatology needs �Morphology �Configuration �Distribution
Morphology � Primary lesions � Secondary lesions � Special lesions
Primary lesion Macule Patch Definition Flat, circumscribed, change in colour/texture of skin w/o surface elevation /depression (Non palpable)<1 cm Well-demarcated, circumscribed, change in colour of the skin >1 cm
Primary Skin Lesion Macules Patches
Types of macules
Primary lesion Papule Plaque Definition Circumscribed, solid, raised lesion <0. 5 cm Circumscribed, solid, plateau-like lesion >0. 5 cm
Primary lesions Plaque Papule
Primary lesion Nodule Cyst Definition Solid raised lesion, > 0. 5 cm diam + deeper component Encapsulated lesion with epithelial inner lining containing liquid or semisolid material Nodule
Primary lesion Nodule Cyst Definition Solid raised lesion, > 0. 5 cm diam + deeper component Encapsulated lesion with epithelial inner lining containing liquid or semisolid material
Primary lesion Vesicle Bulla Definition Circumscribed, Fluid filled, raised lesion <0. 5 cm Circumscribed, Fluid filled, raised lesion >0. 5 cm Circumscribed,
Primary lesion Vesicle Bulla Definition Circumscribed, Fluid filled, raised lesion <0. 5 cm Circumscribed, Fluid filled, raised lesion >0. 5 cm Circumscribed,
Primary lesion Pustule Abscess Definition Well-circumscribed, elevated lesion containing visible purulent exudate Localized accumulation of pus in the dermis/ subcutaneous tissues
Primary lesion Pustule Abscess Definition Well-circumscribed, elevated lesion containing visible purulent exudate Localized accumulation of pus in the dermis/ subcutaneous tissues
Primary lesion Wheal Telangiectasia Definition Evanescent , edematous , plateau-like elevations of various sizes Persistent dilatation of dermal capillaries, visible as fine, bright-red streaks or in a net-like pattern
Primary lesion Wheal Telangiectasia Definition Evanescent , edematous , plateau-like elevations of various sizes Persistent visible dilatation of dermal capillaries, visible as fine, bright-red streaks or in a net-like pattern
Primary lesion Purpura Definition Reddish discoloration of skin or mucous membrane, non- blanchable due to extravasation of red blood cells Petechiae : < 0. 3 cm Purpura : 0. 3– 1 cm (3– 10 mm) Ecchymoses: > 1 cm
Secondary skin lesions � � � � Scale Crust Eschar Erosion Ulcer Fissure Excoriation Lichenification
Layers of the skin
Secondary lesion Definition Scale Laminated masses of keratin resulting in perceptible flakes on the skin surface Crust Hardened deposits resulting from drying of serum, blood or purulent exudate on the surface of the skin (F)
Secondary lesion Definition Scale Laminated masses of keratin resulting in perceptible flakes on the skin surface Crust Hardened deposits resulting from drying of serum, blood or purulent exudate on the surface of the skin (F)
Secondary Definition lesion Fissure Linear, sharply defined , deep cleft through the epidermis or into the dermis Erosion Loss of all or portions of the epidermis Ulcer Full thickness loss of continuity of epidermis plus some portion of the dermis associated with molecular death
Secondary Definition lesion Fissure Linear, sharply defined , deep cleft through the epidermis or into the dermis Erosion Partial, Focal loss of superficial epidermis Ulcer Full thickness loss of continuity of epidermis plus some portion of the dermis associated with molecular death
Secondary Definition lesion Excoriation Punctate or linear abrasion produced by mechanical means, usually involving only the epidermis Eschar Black, hard crust resulting from tissue necrosis of the epidermis and/or dermis
Secondary lesion Definition Lichenification Thickening of the epidermis, hyperpigmentation and accentuation of skin markings in response to prolonged rubbing
Secondary lesion Definition Lichenification Thickening of the epidermis, hyperpigmentation and accentuation of skin markings in response to prolonged rubbing
Secondary lesion Definition Pokiloderma Pigmentation (Hypo/ Hyper), atrophy, telangiectasia
Secondary lesion Definition Sclerosis Diffuse / circumscribed induration of the skin (dermal fibrosis) Induration Firm and thick skin due to dermal involvement
Secondary lesion Definition Sclerosis Diffuse / circumscribed induration of the skin (dermal fibrosis) Induration Firm and thick skin due to dermal involvement
Secondary lesion Atrophy Definition Loss of tissue characterized by the loss of normal skin markings
Special Lesions
Special lesion Definition Burrow Wavy, Slightly raised, brownish, tortuous, thread like tunnel in the epidermis that houses scabies mite: Sarcoptes scabiei var hominis
Special Lesion Definition Comedone Papule plugging sebaceous follicle , containing sebum and cellular debris Open Papule with a dilated central opening filled with blackened keratin (open comedo or blackhead)
Special Lesion Definition Milia A tiny white cyst lined by epithelium containing lamellated keratin
Special Lesion Definition Target Lesion These are less than 3 cm diameter 3 zones; Central zone of dusky erythema/purpura Middle paler zone of oedema Outer ring of erythema with a well-defined edge
Special Lesions
Special Lesion Definition Alopecia Loss of hair from a normally hairy area
Distribution • Generalised : all over the body • Widespread : involving large areas or extensive • Localized : Restricted to one/ some area or the body • Flexural : Body folds like groin, neck, behind ears, popliteal and antecubital fossa
TERMS USED TO DESCRIBE DISTRIBUTION ( The pattern of spread of lesions) •
• Extensor : knees, elbows, shins • Pressure areas : Sacrum, buttocks, ankles, heels • Symmetrical : similar distribution on both sides of the midline • Asymmetrical : dissimilar distribution on both sides of the midline • Photosensitive : over areas exposed to the sun • Acral : pertaining to peripheral parts
TERMS USED TO DESCRIBE CONFIGURATION ( Pattern or shape of grouped lesions) • Discrete : individual lesions separated from each other • Confluent : Lesions merging together • Linear : In a line • Annular : Like a circle or a ring • Target : Group of rings inside each other ( concentric) • Discoid/ Nummular : Like a coin
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