Immune-mediated skin disease Flashcards
what is immune-mediated skin disease?
when the immune system fails to tolerate self-antigen and mounts an immune response to normal skin components
what causes primary immune-mediated skin disease?
idiopathic
what causes secondary immune-mediated skin disease?
trigger - toxin, drugs, bacteria, virus…
what are the key points to look for on an exam of a dog with suspected immune-mediated skin disease?
primary lesions
distribution of lesions
signalment/breed
what are the advantages of using cytology for immune-mediated skin disease?
easy, cheap, rapid
determines if sterile or not
determine type of inflammation
what are the two main sampling techniques used for cytology of immune-mediated skin disease?
direct impression smear
FNA
what lesions is direct impression smears useful for sampling?
pustules, exudative lesions (erosions/ulcers), draining tracts
what are skin biopsies and histopathology used for in immune-mediated skin disease cases?
getting a definitive diagnosis
what are the key points to remember when taking skin biopsies to use for immune-mediated skin disease diagnosis?
take at least three
sample primary lesions
sample range of lesions
sample entire lesion if possible
avoid erosions/ulcers
why are erosions/ulcers avoided when taking skin biopsies?
missing the epidermis so can’t diagnose anything that may be happening in this layer
what skin lesions can be seen in immune-mediated skin disease cases?
pustules
plaques/nodules
erythematous macules/patches
hypopigmented macule/patches
alopecia
vesicles
erosions/ulcers
crusts
purpura
scale
what are the main primary lesions seen with immune-mediated skin disease?
pustules
plaques/nodules
erythematous macules/patches
hypopigmented macule/patches
what are the least helpful lesions when trying to make a differential diagnosis for immune-mediated skin disease?
erosions, ulcers, crusts
what are crusts?
dried exudate on skins surface
what can crusts form from?
pus from pustules
exudate from ulcers/erosions
blood
what is the list of differentials for pustules?
bacterial infection (pyoderma)
pemphigus foliaceus
superficial pustular drug reaction
superficial pustular dermatophytosis
what are the two immune-mediated skin diseases that cause pustules?
pemphigus foliaceus
superficial pustular drug reactions
what is the lesion distribution for Memphis foliaceus?
footpads, pinnae, muzzle, ocular, lateral flanks
what disease are acantholytic keratinocytes seen with?
pemphigus foliaceus
why do we get acantholytic keratinocytes with pemphigus foliaceus?
auto-antibodies target desmosomes (these link the keratinocytes in the dermis) and hence the keratinocytes separate and become rounded
what do desmosomes do?
link keratinocytes in the dermis
what is the most common immune-mediated skin disease of dogs?
pemphigus foliaceus
in general how fast of an onset do immune mediated diseases have?
acute onset
what age dogs get eosinophilic furunculosis of the face?
young adults
is eosinophilic furunculosis of the face pruritic?
yes, very intense
what lesions are associated with eosinophilic furunculosis of the face?
eroded/ulcerated plaques and nodules
what is folliculitis?
inflammation of hair follicle
what is furunculosis?
breakdown/bursting of hair follicle
what age dog is sterile granulomatous dermatitis and lymphadenitis?
young puppies (juvenile cellulitis)
is sterile granulomatous dermatitis and lymphadenitis pruritic?
no (but is painful)
what lesions are seen with sterile granulomatous dermatitis and lymphadenitis?
follicular nodules (furunculosis), plaques, diffuse swelling, alopecia, lymphadenomegaly
what is the distribution of sterile granulomatous dermatitis and lymphadenitis lesions?
face (and lymph nodes)
what is the prognosis of sterile granulomatous dermatitis and lymphadenitis?
good
what is the distribution of sterile nodular panniculitis lesions?
trunk
what are the types of cutaneous lupus erythematosus?
vesicular (rapid onset and rare)
facial discoid lupus erythematosus (chronic and common)
generalised discoid lupus erythematosus (chronic)
mucocutaneous lupus erythematosus (chronic)
exfoliative cutaneous lupus erythematosus (chronic)
what is the most common type of cutaneous lupus erythematosus?
facial discoid lupus erythematosus
what breed is predisposed to discoid lupus erythematosus?
German shepherds
what lesions are seen with facial discoid lupus erythematosus?
loss of cobblestone appearance of nasal planum
hypopigmented macules/patches
erosions, ulcers, crusting
black to blue to pink pigment change
what are the main types of erythema multiforme?
major and minor
what disease is target lesions seen in?
erythema multiforme
what types of erythema multiforme have target lesions?
minor and major
is erythema multiforme pruritic?
no
what can trigger erythema multiforme?
virus, drugs, vaccine, infection, neoplasia, food, idiopathic
what is the primary lesion of erythema multiforme?
annular erythematous macule (target lesion)
what is the distribution of lesions of erythema multiforme?
ventral abdomen (can be generalised mucosa)
what type of inflammation is seen on cytology of dogs with erythema multiforme?
sterile non-specific inflammation
what is the main finding on histopathology of erythema multiforme?
keratinocyte apoptosis
what aged dogs are effected by hyperkeratotic erythema multiforme?
older
what breed is predisposed to uveodermatologic syndrome?
akita
what aged dogs are effected by uveodermatologic syndrome?
young to middle aged
is uveodermatologic syndrome pruritic?
no
what lesions do dogs with uveodermatologic syndrome have?
bilateral uveitis
hypopigmented macules
what is the distribution of uveodermatologic syndrome lesions?
face, nose, lips, periocular skin (occasionally footpads)
are disease cause immune-mediated alopecia?
sebaceous adentitis
alopecia areata
dermatomyositis
ischaemic dermatopathy
post-injection alopecia
what breeds are predisposed to sebaceous adenitis?
poodle, akita, vizsla
is sebaceous adenitis pruritic?
no
what lesions are seen with sebaceous adenitis?
partial alopecia and poor coat quality
follicular casts and scale
what is the distribution of sebaceous adenitis lesions?
generalised
is alopecia areata pruritic?
no
where are alopecia areata lesions distributed?
head/face
what aged dogs get dermatomyositis?
young
what is dermatomyositis also known as?
ischaemic dermatopathy
what breed is predisposed to dermatomyositis?
collies (or similar)
is dermatomyositis pruritic?
no
what lesions are associated with dermatomyositis?
focal/multifocal alopecia
variable hyper/hypopigmentation
scaling
erosions/crusting
what is the distribution of lesions associated with dermatomyositis?
face and extremities
