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- Papule: Due to infiltration of inflammatory cells
- Example: flea bites, sarcoptic mange, bacterial folliculitis
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- Pustule: small, circumscribed elevation- contain mostly neutrophils
- Intraepidermal, follicular, non-follicular
- Examples: bacterial infection, Pemphigus foliaceus
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Hint: Many papules together
- Plaque: Palpable, flat-top elevation
- Formed by coalition of papules
- Examples: Eosinophilic plaque in cats (cutaneous hypersensitivity)
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Hint: Appear and disappear within minutes to hours
- Wheals (Hives): Sharply circumscribed, raised lesion
- Consists of edema
- Examples: Urticaria, insect bites
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- Macule: Flat, non-palpable, circumscribed discoloration <1 cm
- No surface elevation or depression
- Examples: Vitiligo, Lentigo, Acute erythema
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- Patch: Flat, non-palpable, circumscribed skin discoloration
- No surface elevation or depression
- Examples: Vertiligo, Lentigo, Acute erythema
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- Vesicle: Sharply, palpable, circumscribed, elevated lesion <0.5cm
- Example: viral disease, autoimmune disease
- Do impression smear to differentiate between PUSTULE and VESICLE
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Hint: Bigger form of vesicle
- Bulla: Sharply circumscribed, palpable, elevated lesion > 0.5cm
- Contains fluid
- Example: Autoimmune disease
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Hint: will extend into dermis
- Nodule: Solid, circumscribed, elevated lesion >1cm
- Examples: Neoplasia (inflammatory cutaneous lymphoma), Granuloma
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- Cyst: A nodule that contains fluid or semisolid material
- Examples: follicular cyst, infundibular cyst, Acne
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Hint: sometimes called "Scab"
- Crust: colleciton of cellular debris, dried exudate, inflammatory cells, blood
- Regression from Primary lesions: pustules,vesicles, bulla
- Example: later stage of Pemphigus foliaceus
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Hint: can heal without scarring
- Erosion: A partial loss of epidermis
- Does NOT penetrate basement membrane
- Examples: Erythema multiforme
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Hint: big sister of erosion
- Ulcer: A full loss of epidermis
- Will penetrate BEYOND basement membrane
- Heals with scarring in chronic cases
- Lesion will usually bleed easier than erosion
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Hint: caused by scratching
- Excoriation: Linear erosion induced by scratching or trauma
- Seen in puritic dermatoses
- Examples: Atopic dermatitis, scabies, pyoderma
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Hint: NOT caused by trauma
- Fissure: Vertical loss of epidermis and dermis which sharply defined walls/crack in skin
- Found in foot pads and nose
- Example: Hepatocutaneous syndrome
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Hint: you don't need one. Figure it out
- Scar: A formation of new connective tissue (fibrosis)
- Implies prior dermo-epidermal damage
- Example: Cutaneous lupus erythematosus
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Hint: Footprint of a pustule
Epidermal collarette: circular ring of scales, small and does not expand
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- Lichenification: Marked thickening of all layers of the epidermis
- Resembles tree bark
- Caused by chronic rubbing/scratching
- Accentuation of skin lines
- Examples: canine atopic dermatitis
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- Hyperkeratosis: Increase in the thickness of the stratum corneum
- Associated with low-grade trauma, secondary infection, other skin diseases
- Example: Atopic dermatitis with malassezia dermatitis
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Hint: caused by disease such as dermatophytosis
- Spontaneous Alopecia: Border of lesion usually have a sharp margin
- Tip of the hair not affected
- Easily epilate hair shafts
- Example: dermatophytosis, demodicosis, ischemic dermatopathy
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- Self-Induced Alopecia: Border of lesion may have indistinct margin
- Tip of hair usually broken
- Hair not easily epilated
- Exampled: any disease that could cause puritis and pain
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Hint: sometimes called "flakes"
- Scale: Accumulation of loose fragments of the stratum corneum
- Due to disorder of maturation of epidermis or glandular secretions
- Primary lesions: Primary seborrhea of Cocker spaniel, Sebaceous adenitis, Ichthyosis
- Secondary lesions: Xerosis (dry skin), Flea allergy dermatitis, Canine atopic dermatitis, Pyoderma
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Hint: accumulation of stuff....
- Follicular Cast: Accumulation of keratin and sebaceous material that adheres to the hair shaft
- Example: primary seborrhea, dermatophytosis
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- Comedo: Dilated hair follicles filled with cornified cells, and sebaceous and sweat glands secretions
- Example: feline chin acne, demodicosis
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Hint: What is the color of skin lesion?
- Erythema: redness of skin, caused by congestion of blood vessels in dermis
- Blanches (disappears) on pressure- diascopy
- Examples: Allergic dermatosis, cutaneous drug reaction
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Hint: what color is the skin lesion?
- Petechia: dark red to purple coloration, caused by extravasation of RBC into dermis (hemorrhage)
- Does NOT blanch on pressure
- Petechia < purpura < ecchymosis
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- Hypopigmentation: lighter than normal skin color
- Different than Depigmentation
- Examples: Vitiligo, Cutaneous lymphoma, Albinism, Uveodermatologic syndrome
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- Hyperpigmentation: darker than normal skin color
- Example: Lentigo si
- mplex, Hypothyroidism, Post-inflammatory
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