Skin Pathology Flashcards
What 2 types of skin lesions may be present?
1* - direct consequence if the disease process
> eg. macule, nodule, tumour, wheal, vesicle, bulla, patch, papule, pustule, comedo, follicular cast, alopecia, scale, crust
2* - evolve from 1* lesion or caused by self trauma (may obscure 1* lesion)
> eg. epidermal colarette, scar, excoriation, erosion, ulcer, fissure, lichenification, hyperpigmentation, callus
Define wheals
- discrete focus of dermal oedema
- eg. those seen with intra-dermal skin testing
Define angioedema
- more extensive wheal
- oedema affecting whole body region
What patterns of inflammation may be seen with skin disease?
- perivascular
- diffuse/interstitial
- nodular
- panniculitis
- interface
How does normal skin differ on a single animal?
- haired skin thinner epidermis
- hairless skinner thicker epidermis
Define hyperkeratosis
^ stratum corneum, accumulation of loose fragments -> scale
Define hyperplasia
^ stratum spinosum (thickening of living cell layer, acanthosis)
What are follicular casts and when are they seen?
Accumulation of keratinous debris around the hair shaft
Define comedo
- dilated hair follicle plugged with keratinous and sebaceous debris
What is perivascular dematitis? How is it classified further?
> stereotypical/classical reaction to a multitude of pathologies! If skin is red and itchy: probably “hyperplastic, superficial, perivasc. derm.”
may be due to allergy/parasites/infection
- prominance of dermal blood vessels
- leucocytes recruited
- usually + epidermal hyperplasia
superficial/deep plexus involved?
predominnat cell type?
Define papule. Eg of disease that may cause papules?
- solid palpable skin elevation <1cm diameter
- e g. FAD
Define plaque. Which species are these commonly seen in?
- larger, flat-topped elevation caused by extension and coalition of papules
- often seen in horses (viral transmission)
Define pustule
Discrete elevation of the epidermis containing pus (cf. abscess dermal/subcut)
Define abscess
Demarcated dermal or subcutaneous acumulation of pus (cf. pustule epidermal)
Potential causes/pathologies of intraepidermal pustular dermatitis?
> Neutrophilic - pyoderma - sterile disease eg. pemphigus > Eosinophilic - ectoparasite infestation - hypersensitivity