Autoimmune Dermatoses Flashcards
Patterns
Pyoderma
Ventrum
Patterns
Demodicosis
Head
Legs
Paws
Patterns
Scabies/Notoedres
Pinnae
Patterns
Endocrine
Flanks
Tail tip
Symmetrical
Autoimmune disease is…
Implies the body is attacking a self-antigen
Antibodies or activated lymphocytes develop against it-self and causes lesions
Immune-mediated diseases is…
Implies a foreign antigen (protein) triggers an immunological reaction
Antigens:
Drugs
Bacteria
Viruses
Auto-immunity development:
Cell type and action
Lymphocytes which respond to:
Allergies (cytokines; recruit other cells)
Immune response (antigens)
Reactive lymphocytes:
Cleared in the thymus of normal individuals (tolerance) b/c are too active
Auto-immunity development:
Where do things go wrong?
Breakdown in tolerance (reactive lymphocytes stay in circulation) very active lymphocytes
Cross reactivity with self and foreign antigen
Drugs
Infectious agents
Autoimmune Disease
Generalities
Skin = target organ
Hypersensitivity reactions:
Type II
Type III (immune complex)
Unknown cause
Commonly seen in middle-aged animals
Pemphigus (KNOW)
What is it?
Autoimmune vesicobullous to pustular skin disease characterized by acantholysis (rupturing of kerotinocytes)
Pemphigus (KNOW)
Two main subtypes
Pemphigus foliaceus (more common) Pustules and crusts
Pemphigus vulgaris (rare) ulceration of basal cell layer
Keratinocytes are held together by…(2 things)
Keratinocytes are held together by adhesions:
Desmosomes (closure to superficial layer)
Hemidesmosomes (attaches keratinocytes to basal cell layer)
Pemphigus foliaceus
Pathogenesis
Adhesions of desmosomes mediated by specialized proteins:
Desmogleins
Desmocollins
These are targeted by Pemphigus
Pemphigus foliaceus
Pathogenesis in dogs
Autoantibody response primarily involves IgG
Desmocollins 1 glycoprotein in the desmosome is the major autoantigen
Pemphigus foliaceus
Signalment
Dogs
Genetic factors may play role in development
Middle age
Akitas
Chows
Pemphigus foliaceus
Cats
Median age: 5 but really any age, any breed, any sex can get it
Pemphigus foliaceus Triggering Factors (4 main)
UV light Allergies Drugs Medications Idiopathic in cats
Pemphigus foliaceus
UV light mechanism
Not well understood
Lesions seem to worsen in the summer and improve in the winter
Pemphigus foliaceus
Allergies
Potentially triggers due to chronic inflammation
Pemphigus foliaceus
Drug triggers
Activation of proteolytic enzymes in skin and autoantibodies against desmosomes
Pemphigus foliaceus
Medications
Cephalexin
Clavamox
TMS
Guaranteed and => taken off the market (unsure what exactly was in them that did this)
Promeris
Certifect
Pemphigus foliaceus
Lesions Dogs
Skin lesions:
Pustules
Crusts
Erosions
May think pyoderma BUT these dogs have excessive lesions
Pemphigus foliaceus
Location of lesions Dog
Face/muzzle Bridge of nose Periocluar skin Ears Paws + Generalized = Rare
Note: do not usually see pyoderma here
Pemphigus foliaceus
Skin Lesions Cat
Crusts
Pustules
Erosions
Alopecia
Pemphigus foliaceus
Location of lesions Cat
Head
Face
Ears
Claw folds (caseous material, cheese like)
Peri-areolar (crusting around nipple) - unique
Pemphigus foliaceus
Clinical Signs
Fever
Lethargy
Anorexia
Lymphadenopathy
Pruritus; up to 50% of the dog cases and 80% of cat cases
Pemphigus foliaceus
DfDx
Superficial pustular dermatophytosis
Bacterial (Staph.); produces toxins that target desmosomes and mimic PF
Demodex
Scabies/Notoedres
Pemphigus foliaceus
Diagnosis (broad)
History PE Dermatologic exam Cytology (rule out dermatophytosis) Negative skin scrapings (demodex, scabies, notoedres)
Histopathology; a MUST because treatment requires steroids and must confirm prior to steroid treatment
Pemphigus foliaceus
Cytology Results
Take 1-5 samples; slightly lift crust and dab area
Acantholytic keratinocytes (immature keratinocytes)
Non-degenerative neutrophils
Absence of organism
Pemphigus foliaceus
Biopsy
Subcorneal/intracorneal
Acantholytic keratinocytes
Pustules
Absence of organisms
Pemphigus foliaceus
Prior to biopsy…
Must have been off steroids for 2-3 weeks; steroids will suppress the acantholytic keratinocytes
Treat secondary infection(s); bacteria can cause acantholysis
Sample less active lesions; pustules are the best but undisturbed crusts will work
Take multiple samples of only lesioned tissue
Do NOT prep site
Pemphigus Erythematosus
Characteristics
Uncommon
Benign variant of pemphigus foliaceus