L3-Autoimmune disorders Flashcards
autoimmune diseases facts
often very specific histologic changes
dx test of choice is biopsy
BIOPSY THESE LESIONS
autoantibodies against host protein of some sort
vast majority- cannot tell inciting cause/ trigger
drugs, neoplasia, infection, genetics, etc.
Phemphigus diseases
group of diseases with pustules, vesicles, bullae, ulcers
- loss of adhesion between cells- ACANTHOLYSIS
autoantibodies against proteins that connect epithelial cells of epidermis
ancillary diagnostic tests: IF or IHC for antibodies in specific locations
Pemphigus Foliaceous
most common and milder form in animals- dogs, cats, horses
antibodies against DESMOCOLLIN-1
desmosome-connects epithelial cells together
can arise spontaneously, triggered by drugs
pustules that rupture- crusting and scaling
NASAL PLANUM, pinnae, periocular, footpads, clawbeds, coronary band
often bilaterally symmetrical esp, over face
horses: often starts on legs or face- acantholytic keratinocytes
Pemphigus vularis
more severe, rare form: dog, cat, horse, goat
- autoantibodies against desmoglein 3
vesicles and bullae are fragile, rupture easily
roughly circular, shallow flat erosion or ulcer
MUCOCUTANEOUS MEMBRANES, junctions, ORAL MUCOSA
Bullous pemphigoid
(not a true pemphigus lesion)
dogs, cats, horses, yucatan minipig
autoantibody against hemidesmosome proteins-BASEMENT MEMBRANE
vesicles, bullae, ulcers- can rupture, no ACANTHOLYTIC KERATINOCYTES
dogs- MM, lips, face, axilla, groin
cats- lips, oral mucosa, pinnae
horses oral mucosa
pigs- rump and back
Lupus erythematosus
spectrum of disease from mild to life threatening
cutaneous- skin specific effects- can be breed specific
systemic- joints,kidney
TYPE III HYPERSENSITIVITY: systemic, more life threatening, more severe, GSD predisposed, polyarthritis, glomerulonephritis, thrombocytopenia, anemia
MUCOCUTANEOUS JUNCTIONS, FACE,lips nose and ears
ulceration, scaling,alopecia
diagnostics: antinuclear antibody titer (ANA)
Drug reactions
dogs, cats, horses: pretty much any drug can cause reaction looks like any dermatosis
history of lesions with recent administration: goes away when drug removed, happens again if drug is given
- pcns, sulfonamides ( TMS), cephalosporins, antibiotics
levamisole, triamicinolone, nsaids
Erythema multiforme (EM)
: stevens johnson syndrome
dogs, cats, horses, cattle, pigs
EM tends to be milder, not caused by drugs
can be idiopathic in older dogs
misdirected immune response against keratinocytes
EM: circular to linear areas of erythema- target like lesions- ulcers: trunk, axilla, groin, face
Erythema multiforme TEN
Toxic epidermal necrolysis
TEN tends to be more severe, caused by drugs
misdirected immune response against keratinocytes
TEN: severe ulceration widespread and painful
mucocutaneous junctions, footpads, systemic signs, fever and lethargy
Plasma cell pododermatitis
rare disorder in cats- all breeds
possible link to FIV positive status
soft, non painful swelling of multi footpads on muti paws
central metacarpal and metatarsals pads most common
can ulcerate over time
footpad surface is cross hatched
( biopsy/plasma cell heavy)
Viral diseases
some viruses have tropism for epithelium
some are systemic that happen to cause skin lesions
cutaneous viral disease more common in food animals than pets
similar viral families cause disease in many species
EX: pox virus
pre-mortem test exist ( viral PCR, virus isolation
can also send biopsy
we can do IHC or pcr for the viral antigen
- inclusion bodies
Poxvirus
large family of dna virus
highly epitheliotropic- skin and systemic disease
many host specific
some can affect many species
some are zoonotic
rout of infection: resp. or cutaneous
degenerative changes to epithelium- VESICLES
becomes umbilicated papules w/ depressed center and erythematous border
histo: intracytoplasmic inclusions
Parapoxvirus/ Orf virus
contagious pustular dermatitis
sheep and goats- young
commissures of lips, spread to muzzle and face
more proliferative
- wear gloves
Zoonotic
parapoxvirus: pseudocowpox
cattle-endemic
zoonotic
ring or horseshoe shaped crust on teat or udder
Parapoxvirus: bovine papular stomatitis
cattle
zoonotic
muzzle, lips, mouth
central necrosis and crusting
-rule out hand foot and mouth disease
Capripox
all are transboundary not found in the US
sheeppox- sheep all ages, vesicles to pustules on sparsely wooled area
goatpox- goats, lesions similar to sheeppox
lumpy skin disease:
cattle buffalo
multi skin nodules
undergo necrosis and sequestration
fever, lymphadenopathy
swinepox
occurs worldwide
usually mild, growing piglets
ventral and lateral abd. thorax, medial thigh
erythematous macules and plaques
Avipox/fowlpox
chickens, turkeys, other domestic birds ( canaries)
cutaneous or dry form
most common
papules, vesicles, crust on NON FEATHERED SKIN
tends to be proliferative as well
head, neck, legs and feet
papillomavirus
dna virus
tropism for cutaneous and mucosal squamous epithelium
general host specific
exceptions: bovine papillomavirus- equine sarciods
cervid papillomavirus multi species
cause PAPILLOMAS- benign tumors of epidermis
can also cause fibropapillomas- proliferation of dermis
can be found anywhere and in any species
psittacine beak and feather disease
caused by circovirus- dna virus
targets basal layer of feather follicular epthelium
deformities due to necrosis of basal epithelium
thymic and bursal necrosis-immunosuppression
PROGRESSIVE SYMMETRIC FEATHER DYSTROPHY AND BEAK OVERGROWTH
feathers: short, clubbed, deformed, curled, with thickened/ retained feather sheaths
beak deformities: elongation, fracture, delamination, palatine necrosis
CLAW MALFORMATIONS
Herpesvirus
dna viruses
important systemic diseases
intranuclear inclusions
3 main types: alpha, beta, gamma
herpesvirus 3 types
alpha: often cause necrosis of varous tissues
cause majority of herpes diseases
beta: have large intranuclear inclusions
mainly include cytomegaloviruses
gamma: oncogenic or proliferative diseases- often cause neoplastic disease
herpes virus: bovine herpesvirus 2
bovine ulcerative mammillitis
alphaherpes virus
generalized- pseudo lumpy skin disease
looks like lumpy skin disease- capripox, but no necrosis
localized disease:
infeciton of teat or nipple in dairy cattle
swollen and painful, plaques on skin
felid herpesvirus-1
alphaherpes virus
ulcerations on haired skin of face and nasal planum
crusts, ulcers, vesicles
Herpesvirus: Gallid herpesvirus 2
mareks disease
alpaherpesvirus
mareks- lymphoproliferative disease in chickens T- cell lymphoma
route of infection: inhalation of feather dander
infection of feather follicle epithelium
virus is shed in feather dander, site of complete viral replication
cutaneous mareks disease- feather follicle enlargement, skin reddening
most common in broilers- causes carcass condemnation
canine distemper
morbillivirus-rna virus
causes systemic disease with resp. and cns signs
also has cutaneous signs
hyperkeratosis of footpads and nose plus or minus secondary pyoderma
hard pad disease
ORTHOKERATOTIC AND PARAKERATOTIC HYPERKERATOSIS of footpad, nose
has both intranuclear and intracytoplasmic inclusions
iridovirus
LYMPHOCYSITS DISEASE: most common viral infection of aquarium fish
infects dermal fibroblasts- cellular hypertrophy
salt like dusting- small cream colored nodules on skin and fins
large hypertrophied dermal fibroblasts
basophilic cytoplasmic inclusion material
Dx: tail clipping/ biopsy
fungal disease: candidiasis
thrush-
dogs, cats, pigs, horses, goats
normally present at mucocutaneous junctions of body orifices
immune suppression- is usually underlying cause
papule and pustules- well delineated ulcers with erythematous borders
moist white- grey exudate
can occur anywhere on skin
yeasts, hyphae, pseudophyphae
fungal: malassezia
malessezia pachydermatis:
most common in skin infections
normal flora of skin
overgrowth due to some disturbance to skin or immune system
most common in dogs
excess cerumen, high humidity, moist conditions
less common in cats- black ceruminous otitis, chin acne
alopecia, erythema, greasiness, hyperpigmentation
ears, axilla, inguinal region, inerdigital skin, nail/claw
diagnostics: skin/ ear cytology
fungal: dermatophytosis
Ringworm • Confined to keratin layers of skin, hair, claws
• Requires actively growing hairs for survival • Microsporum, Trichophyton, Epidermophyton
• M. canis, M. gypseum, T. mentagrophytes • Route of infection: direct, fomites
• Young age, stress, poor nutrition, warm humid areas
• Self-limiting in healthy animals • Progressive circular areas of scaling and alopecia,
crusting
• Head, face, neck, limbs
• Hyphae found in hair follicles
• Diagnostics: fungal culture (use toothbrush)
fungal: feline dermatophytic pseudomycetoma
• Atypical, rare form involving deep dermis
and SQ tissue – usually caused by M. canis • Persian cats almost exclusively - can affect
other long-haired breeds • Hyphae in deep dermis form mycetoma-like
granulomas (lack cementing substance, less
hyphae) • One or more SQ nodules; +/- ulceration
and draining tract
• Ye l l o w g ra n u l e s • Dorsal trunk or tail base
fungal: dimporphic fungi
Thermally dependent • Yeast at >37C • Mycelial form in cooler temps • Cause pulmonary, cutaneous,
or disseminated disease
• Histoplasma capsulatum • Blastomyces dermatitidis • Cryptococcus neoformans • Coccidioides immitis • Sporothrix schenckii
• Diagnostic: culture or cytology
fungal: blastomycosis
Blastomyces dermatitidis
zoonotic
• Dimorphic fungus • Route of infection: inhalation or wounds
• Dogs, rare in cats • Non-healing wounds, dermal mass
• May have draining tract, ulcerative • Diagnostic: cytology or histopath
• Do NOT culture
• Yeast: 5-15 uM, round
• BROAD-based budding • Granulomatous to pyogranulomatous inflammation • Can be extracellular or within macrophages
fungal: cyrptococcus
zoonotic
Cryptococcus neoformans • Most common systemic mycotic disease of
cats • Route of infection: inhalation of
contaminated dust
• Primary infection in nasal cavity à spreads out
to skin • Thick mucopolysaccharide capsule – avoids
phagocytosis from macrophages
• Ulcerative, weeping lesions along nose,
nodular mass in nasal cavity • Cytology:
• Spherical, 2-10 uM diameter yeast
• THICK capsule (up to 30 uM)
• Soap bubble appearance
• Minimal inflammation
fungal: sporotrichosis
zoonotic
Sporothrix schenckii
• Opportunistic, dimorphic fungus
• Disease usually in cats, horses, dogs (hunting
usually) • 3 clinical forms: cutaneous (dogs, cats),
cutaneous-lymphatic (horses), disseminated
(cats)
• Infection mainly by wound contamination,
puncture wounds • Nodules on head, pinnae, trunk, distal limbs
with red-brown purulent exudate
• Has draining tract • Horses: nodules follow the course of
lymphatics, which are often thick/corded • Diagnostics: culture or cytology
• Yeast: cigar-shaped, clear cell wall
• Extracellular or in macrophages
• Pyo/granulomatous inflammation
• Numerous organisms in cats, rare in others
fungal: cutaneous oomycosis
zoonotic
Pythium insidiosum or Lagenidium sp. • Aquatic molds, opportunistic fungal-like
organism
• Warm, stagnant water • Route of infection: wounds • Horses: distal limbs (distal to carpus and hock)
• Nodules à large masses of granulation tissue,
ulcerative • KUNKERS –grey-white to yellow, coral-like
concretions in these tracts
• Clear spaces outlining hyphae (HARD TO SEE!)
• Dogs: ulcerative nodules with draining tracts
• Head, face, limbs • Diagnostics: cytology, PCR
• Hard to distinguish between species
• Inflammation: pyo/granulomatous
clear spaces outlining hyphae- hard to see
fungal: chromomycosis
Phaeohyphomycosis • Opportunistic, pigmented (dematiacious) fungi
• Alternaria, Bipolaris, Cladosporium, Curvularia, Exophiala, Ochroconis
• More common in cats, can occur in other species • Usually affects skin/SQ, can go to CNS or disseminated –
infection mainly from trauma or contaminated wound • Melanin synthesis in cell wall thought to be main virulence
factor
width, +/- branching
• Elude host immune response, protection from oxidative burst • Gross:
• Dermal or SQ nodules, +/- ulceration and fistulous tracts
• May be blue-grey or dark in color due to pigment • Histology:
• Intralesional pigmented yeast or hyphae – septate, irregular
