Pathology of the Integumentary System, Pt. 3 Flashcards
What is perivascular dermatitis? Why is it considered nonspecific?
inflammatory cells aggregate around blood vessels
most common response to any injury —> aka superficial perivascular dermatitis, primarily hypersensitivity
What 4 common hypersensitivity disorders cause superficial perivascular dermatitis?
- atopic dermatitis
- cutaneous adverse food reaction
- flea bite hypersensitivity
- ectoparasitism
- histopathology not helpful for finding a cause
What are Type I hypersensitivities mediated by? How does it develop?
IgE
production of IgE causes the immediate release of vasoactive amines and other mediators from mast cells, which later recruits eosinophils
What is pruritus? How does it tend to manifest in dogs and cats? What are 5 common causes?
unpleasant sensation which provokes the desire to scratch (itching) —> mast cell aggregation
chewing, licking, scratching, rubbing, overgrooming
parasites, allergies, inflammation, neurogenic conditions, neoplasm
What is the difference between acute and chronic perivascular dermatitis gross presentation?
ACUTE: edema, erythematous papules, wheals
CHRONIC: alopecia, lichenification, hyperpigmentation
What is the difference between acute and chronic perivascular dermatitis histologically?
ACUTE: vascular dilation, dermal edema, spongiosis, perivascular eosinophils
CHRONIC: epidermal hyperplasia, compact hyperkeratosis, hyperplastic follicular infundibula, sebaceous gland hyperplasia, apocrine gland ectasia, fibrosis
What is utricaria/angioedema? What are 3 common causes? What is seen histologically?
(hives, heat bumps)
acute wheals, erythema, edema, and variable pruritus that typically only lasts 12-24 hours
- drugs
- venomous stings
- biological agents
no lesions or dermal edema
What is the most common cutaneous inflammatory and pruritic disease in dogs? What 3 breeds of dogs are most suscpetible?
canine atopic dermatitis
- terriers
- retrievers
- brachycephalic breeds
What is the typical age of onset of canine atopic dermatitis? How does it present?
1-3 years
generalized pruritis PRIOR to skin lesions
- seasonal***
- nonseasonal
- nonseasonal + seasonal worsening
What are the most common symptoms of canine atopic dermatitis after pruritus? Where on the body is it concentrated?
erythema, alopecia, excoriations, hyperpigmentation, lichenification
head, paws, flexor aspect of elbows, carpal and tarsal joints, axilla, groin, ventrum
Canine atopic dermatitis:
What secondary conditions are common with canine atopic dermatitis?
bacterial pyoderma and Malassezia dermatitis
What is thought to be the pathogenesis of canine atopic dermatitis? How is it diagnosed?
involves skin barrier dysfunction and dysregulated immune responses
diagnoses of exclusion —> allergy testing is only performed when the clinical diagnosis has been made by ruling out all other causes of pruritus/dermatitis
What is canine food allergy? What is the typical age of onset? What are common signs?
adverse reaction to a food or food additive
less than 1 year old
non-seasonal pruritus with variable response to steroids and possible GI signs
- secondary infection is common
How does canine food allergy typically present grossly?
same as atopic dermatitis - erythema, alopecia, excoriations, scales, crusts, hyperpigmentation, and lichenification on face pinnae, axillae, groin, paws, and perianal region
What is the pathogenesis of canine flea allergic dermatitis? Why is it considered seasonal? What is the common presentation and where on the body is it most common?
sensitization to flea saliva proteins through repeated and intermittent flea bites
based on flea activity
hypotrichosis, papules, erythematous plaques, and wheals concentrated on dorsal lumbar area, flanks, tail base, and hindlimbs
What is feline atopic skin syndrome (FASS)?
inflammatory and pruritic skin syndrome of cats manifested by a spectrum of reaction patterns, none of which are specific for this syndrome, and may be associated with IgE to environmental allergens
What are the 4 common cutaneous reaction pattern for FASS?
- miliary dermatitis (MD) - countless papules
- self-induced alopecia (SIA) - overgrooming
- face, head, neck pruritus (FHN)
- eosinophilic granuloma complex (EGC) - plaque
Miliary dermatitis:
cutaneous reaction pattern for FASS
Self-induced alopecia:
cutaneous reaction pattern for FASS