Derm 1 Flashcards
Primary lesion
initial eruption that develops spontaneously as a direct reflection of underlying disease
Secondary lesion
-evolve from primary lesions
-are artifacts induced by the patient or external trauma or medications
Examples of primary lesions
-macule or patch
-papule or plaque
-pustule
-vesicle or bulla
-wheal
-nodule
Examples of secondary lesions
-epidermal collarette
-scar
-excoriation
-erosion or ulcer
-fissure
-lichenification
Lesions that can be primary or secondary lesions
-alopecia
-scale
-scrust
-follicular casts
-comedones
Diagnostic methods
-biopsies
-cytology
-skin scrapings
Pustule
-circumscribed elevation of skin containing pus = inflammation
**does not mean infection though!! Infection is a differential
Macule vs patch
Macule: circumscribed flat area of colour change <1cm diameter
Patch: circumscribed flat area of colour change >1cm diameter
Erythematous macules
-if put pressure and colour stays the same
*if it blanches out than not true macule
Hyperpigmentation
-lentigo
-post inflammatory changes
Hemorrhagic patches
-eg. trauma, vasculitis
Depigmentation
-eg. autoimmune, post inflammatory, cancer
Papule
Solid elevated lesion <1cm diameter
-local cellular infiltrate
Papule
Nodule
-circumscribed solid elevation >1cm in diameter
-usually extends deep into skin layers
*infiltration of inflammatory or neoplastic cells
eg. neoplasia, granulomatous inflammation
Hives/wheal
-sharply circumscribed raised lesion consisting of edema
-associated with allergic rxns or vascular leakage
Tufting of hair
Does not indicate hives! Dont be fooled
Plaques
-flat elevation in skin >1cm in diameter
-coalition of papules = chronic inflammatory disease
Vesicle vs bulla
Vesicle: sharpely circumscribed elevation of epidermis filled with clear fluid <1cm in diameter
Bula >1cm in diameter
**Both RARE to see in dogs and cats because they are weak and rupture so easily with normal grooming behaviours
When do you see vesicles or bullas?
-viral, immune mediated, irritants
Epidermal collarette
-secondary to papule or pustule, vesicle or bullarupture (post inflammatory)
-annular lesion of scales/keratin flakes
**typically bacterial, often misdiagnosed for ringworm
Lichenification
Thickening and hardening of the skin
-often hyperpigmented
-chronic friction or irritation
Erosion vs ulcers
Erosion: shallow epidermal defect that does not penetrate basal laminar zone
Ulcer: break in continuity of epidermis with exposure of underlying dermis
Biopsies of ulcers or erosions
Always take on the edge
Excoriations
Erosion or ulcer caused by scratching, biting, rubbing
Fissure
Linear cleavage into epidermis or through epidermis into dermis
-caused by disease or injury
-may be single or multiple
Scale
-accumulation of loose fragments of horny layer of skin
Primary vs secondary scale
Primary: icthyosis
Secondary: chronic inflammation
Crust
Accumulation of dried exudate, serum, pus, blood, cells, scales, or medications adherent to skin surface
Primary vs secondary crust
Primary= more adherent
*eg. Zinc responsive dermatosis
Secondary= can usually peel off, goo underneath
eg. pyoderma, pruritus
Comedomes
-dilated hair follicle filled with cornified cells and sebaceous material
Primary vs secondary comedomes
Primary: feline acne
Secondary: demodicosis
Follicular casts
Accumulation of keratin and follicular material that adheres to hair shaft extending above the surface of the follicle opening
Primary and secondary follicular casts
Primary: Vit A responsive dermatoses
Secondary: Dermatophytosis or demodicosis
Alopecia
partial or complete hair loss
Primary or secondary alopecia
Primary: endocrine disease (hypothyroidism)
Secondary: pruritus or demodicosis
Hypothrichosis
A form of alopecia
-less than normal amount of hair
Configurations of lesions
-single
-linear
-annular
-coalescing
Annular configuration
-circular; clear or less involved center
Single lesions
one location or multifocal
Coalescing configurations
A confluence of lesions or spreading process
Linear configuration
Linear lesions
-scratching
