Autoimmune Dermatoses Flashcards
(80 cards)
1
Q
Patterns
Pyoderma
A
Ventrum
2
Q
Patterns
Demodicosis
A
Head
Legs
Paws
3
Q
Patterns
Scabies/Notoedres
A
Pinnae
4
Q
Patterns
Endocrine
A
Flanks
Tail tip
Symmetrical
5
Q
Autoimmune disease is…
A
Implies the body is attacking a self-antigen
Antibodies or activated lymphocytes develop against it-self and causes lesions
6
Q
Immune-mediated diseases is…
A
Implies a foreign antigen (protein) triggers an immunological reaction
Antigens:
Drugs
Bacteria
Viruses
7
Q
Auto-immunity development:
Cell type and action
A
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
8
Q
Auto-immunity development:
Where do things go wrong?
A
Breakdown in tolerance (reactive lymphocytes stay in circulation) very active lymphocytes
Cross reactivity with self and foreign antigen
Drugs
Infectious agents
9
Q
Autoimmune Disease
Generalities
A
Skin = target organ
Hypersensitivity reactions:
Type II
Type III (immune complex)
Unknown cause
Commonly seen in middle-aged animals
10
Q
Pemphigus (KNOW)
What is it?
A
Autoimmune vesicobullous to pustular skin disease characterized by acantholysis (rupturing of kerotinocytes)
11
Q
Pemphigus (KNOW)
Two main subtypes
A
Pemphigus foliaceus (more common) Pustules and crusts
Pemphigus vulgaris (rare) ulceration of basal cell layer
12
Q
Keratinocytes are held together by…(2 things)
A
Keratinocytes are held together by adhesions:
Desmosomes (closure to superficial layer)
Hemidesmosomes (attaches keratinocytes to basal cell layer)
13
Q
Pemphigus foliaceus
Pathogenesis
A
Adhesions of desmosomes mediated by specialized proteins:
Desmogleins
Desmocollins
These are targeted by Pemphigus
14
Q
Pemphigus foliaceus
Pathogenesis in dogs
A
Autoantibody response primarily involves IgG
Desmocollins 1 glycoprotein in the desmosome is the major autoantigen
15
Q
Pemphigus foliaceus
Signalment
Dogs
A
Genetic factors may play role in development
Middle age
Akitas
Chows
16
Q
Pemphigus foliaceus
Cats
A
Median age: 5 but really any age, any breed, any sex can get it
17
Q
Pemphigus foliaceus Triggering Factors (4 main)
A
UV light Allergies Drugs Medications Idiopathic in cats
18
Q
Pemphigus foliaceus
UV light mechanism
A
Not well understood
Lesions seem to worsen in the summer and improve in the winter
19
Q
Pemphigus foliaceus
Allergies
A
Potentially triggers due to chronic inflammation
20
Q
Pemphigus foliaceus
Drug triggers
A
Activation of proteolytic enzymes in skin and autoantibodies against desmosomes
21
Q
Pemphigus foliaceus
Medications
A
Cephalexin
Clavamox
TMS
Guaranteed and => taken off the market (unsure what exactly was in them that did this)
Promeris
Certifect
22
Q
Pemphigus foliaceus
Lesions Dogs
A
Skin lesions:
Pustules
Crusts
Erosions
May think pyoderma BUT these dogs have excessive lesions
23
Q
Pemphigus foliaceus
Location of lesions Dog
A
Face/muzzle Bridge of nose Periocluar skin Ears Paws + Generalized = Rare
Note: do not usually see pyoderma here
24
Q
Pemphigus foliaceus
Skin Lesions Cat
A
Crusts
Pustules
Erosions
Alopecia
25
Pemphigus foliaceus
| Location of lesions Cat
Head
Face
Ears
Claw folds (caseous material, cheese like)
Peri-areolar (crusting around nipple) - unique
26
Pemphigus foliaceus
| Clinical Signs
Fever
Lethargy
Anorexia
Lymphadenopathy
Pruritus; up to 50% of the dog cases and 80% of cat cases
27
Pemphigus foliaceus
| DfDx
Superficial pustular dermatophytosis
Bacterial (Staph.); produces toxins that target desmosomes and mimic PF
Demodex
Scabies/Notoedres
28
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
29
Pemphigus foliaceus
| Cytology Results
Take 1-5 samples; slightly lift crust and dab area
Acantholytic keratinocytes (immature keratinocytes)
Non-degenerative neutrophils
Absence of organism
30
Pemphigus foliaceus
| Biopsy
Subcorneal/intracorneal
Acantholytic keratinocytes
Pustules
Absence of organisms
31
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
32
Pemphigus Erythematosus
| Characteristics
Uncommon
Benign variant of pemphigus foliaceus
33
Pemphigus Erythematosus
| Clinical Lesions
Facial distribution (usually bridge of nose)
```
Pustules
Crust
Alopecia
Erosions
Oozing
```
34
Pemphigus Vulgaris
| Background
Vulgar = BAD
Rare
Most severe form of the pemphigus complex
Poor prognosis; decline quickly
35
Pemphigus Vulgaris
| Clinical lesions
Vesicles
Bullae
Ulcers
Crust
36
Pemphigus Vulgaris
| Distribution of lesions
Ears
Foot pads
Mucocutaneous junctions
Oral cavity (80%)
37
Pemphigus
| Treatment
Suppress immune system
Induce remission
Taper to lowest dose (anti-inflammatory) and frequency
Note: if no biopsy confirmation was done and it is ringworm the lesions will get worse
38
Pemphigus
| Treatment Rx Regimen
Glucocorticoids:
Primary choice
Immune-suppressive (2 mg/kg) for 14 days
Recheck; if improving start tappering
Goal: Life-long treatment on anti-inflammatory dose every other day (trying to avoid negative side effects of steroids)
39
Pemphigus
| Glucocorticoids help with...
```
Decrease arachidonic acid
Inhibits inflammatory cytokines
Decrease chemotactic factors and inflammatory cells
Suppress T-cell function
Induce apoptosis of T cells
Suppress B-cell antibody production
```
40
Mycophenolate
| What is it?
Immune-Modulatory Drug
If glucocorticoids did not work this is next best thing; can also use it in combination with steroids to lower steroid dose
41
Mycophenolate
| MOA
Immune-Modulatory Drug
```
Inhibits DNA synthesis
Inhibits macrophages, T, and B cell profliferation
Induces apoptosis of T cells
Suppresses B-cell antibody production
Rapid onset of action (2-4 hours)
```
42
Azathioprine
| What is it?
Immune-Modulatory Drug
Pro-drug; gets transformed into active form
Purine analogue that interferes with nucleic acid synthesis
CANNOT USE IN CATS
43
Azathioprine
| MOA
Immune-Modulatory Drug
Cytotoxic to T cells
Slow onset of action (1-2 weeks)
Side effects:
Fulminant hepatic necrosis with increase of ALT
Bone marrow suppression
Increased risk of infections
DO NOT USE IN CATS because cannot inactivate it
44
Cyclosporine
| MOA
Immune-Modulatory Drug
Calcineurin inhibitor
Prevents activation of T lymphocytes
Blocks pro-inflammatory cytokines and pro-inflammatory pathways
Might be better in maintaining remission opposed to inducing remission
45
Three other auto-immune diseases
Discoid lupus Erythematosus
Systemic Lupus Erythematosus (not common)
Uveodermatologic Syndrome
46
Discoid Lupus Erythematosus
| Background
Second most common auto-immune disease
Lesions limited to nose
Benign disease
Pet feels good
Can be aggravated and/or induced by UV light
47
Discoid Lupus Erythematosus
| Clinical Lesions
```
Depigmentation of nose
Gray/bluish color
Loss of cobblestone appearance
Erosions
Ulcers
Crusting
```
48
Discoid Lupus Erythematosus
| Lesions
Nose
Can extend to:
Bridge of nose
Eyes
Ears
Note: Pemphigus does NOT affect the dose itself!
49
Discoid Lupus Erythematosus
| Diagnosis
Rule out: mucocutaneous pyoderma
Cytology
Biopsy
First treat for pyoderma if no results do a biopsy
50
Discoid Lupus Erythematosus
| Treatment (3)
Tacrolimus:
Very effective topical
Cousin of cyclosporine; too large of molecule to be a topical
Avoid direct sunlight; sunscreen on nose!
Doxycycline/niacinamide
51
Doxycycline/niacinamide
Inhibit matrix metalloproteases
Anti-inflammatory properties
Can take 6-8 weeks to work
52
Immune-Mediated Diseases
Skin changes...
What is important to do at the beginning of the appointment
Skin changes are severe!
```
Thorough history is key:
Travel
Tick-borne
Drug history
Vaccines
```
53
Vasculitis
| What is it?
Seen with immune-mediated disease
Inflammation and destruction of blood vessels which results in ischemic necrosis
=>
Poor blood supply to skin leads to ischemic dermatopathy
54
Vasculitis
| Triggers (4)
Idiopathic
Infectious
Drugs
Immune-mediated
55
Vasculitis
| Idiopathic Triggers
Up to 50% of cases
Especially seen in Jack Russell Terriers
56
Vasculitis
| Infectious Triggers
```
Bacterial
Viral (Parvo, Coronavirus)
Protozoal (Leishmania, Sarcocystis)
Rickettsial (RMSF, Ehrlichia, Babesia)
Fungal
```
57
Vasculitis
| Drug Triggers
```
Injection of foreign protein (vaccines; rabies)
Antibiotics
Ivermectin
Itraconazole
Fenbendazole
```
58
Vasculitis
| Immune-mediated
RARE
Systemic lupus erythematosus
Rheumatoid arthritis
59
Vaculitis
Rabies Vaccine Induced
Breeds
Detected in blood vessels and epithelium of hair follicles
Unsure why this occurs
```
Breeds:
Poodles
Silky Terrier
Pekingese
Bichon Frise
Maltese
```
60
Vasculitis
Rabies Vaccine Induced
Lesions
Circular area of alopecia at site of vaccine
Signs can be seen 2-8 months after vaccination
NO inflammation, papules, or crusts
Note: always important to note where you give injections
61
Vasculitis
Rabies Vaccine Induced
DfDx
Dermatophytosis
| Folliculitis
62
Vasculitis
Ear Tip
DfDx
Rabies Vaccine Induced
Pemphigus (usually on nose though)
Ectoparasites (scabies, notoedres and will be very pruritic)
See notches in ear tip
Painful
63
Vasculitis
| Diagnosis
Clinical signs
History (vaccination times and drug administration)
Rule out: tick borne diseases
Biopsy: rare to see active vasculitis but can see atrophy of hair follicles which is supportive
64
Vasculitis
Rabies Vaccine Induced
Treatment
If rabies vaccine is trigger do not vaccinate; check titers and consult state vet for what to do if titers low
65
Vasculitis
| What type of hypersensitivity?
Type III
Antigen-Complex:
Triggers neutrophils, mast cell degranulation, platelet aggregation
66
Vasculitis
| Repeat exposure can lead to...
Worsening of lesions
Glomerular nephritis due to accumulation of antigen-antibody complex
67
Vasculitis
| Pentoxifylline
Methylxanthine (caffine) derivative
Potent hemorheologic and anti-inflammatory properties:
Helps RBCs to become more deformable which allows for better circualation
Improves mirocirculation
Inhibits:
Cytokines
Leukocyte and platelet adhesion to endothelial cells
Takes 6-8 weeks to be effective
68
Vasculitis
| Doxycycline/Niacinamide
If patient does not respond to Pentoxifylline
Inhibits matrix metalloproteases (anti-inflammatory)
Takes 6-8 weeks to be effective
Usually on this for the rest of their life
69
Symmetrical Lupoid Onychodystrophy (SLO)
| What is it?
Uncommon claw disease
Unknown etiology
Suspected to have a "vasculitic" immune-mediated component (Type III Hypersensitivity)
70
Symmetrical Lupoid Onychodystrophy (SLO)
| Clinical Signs
Acute onset of nail loss (nails literally falling off); onycholysis -separation of nails from quick
onychoschizia -splitting of claws
May affect only a few but will progress
Painful
+/- liking of paws
May get secondary infections (mal-odor, swollen digit)
71
Symmetrical Lupoid Onychodystrophy (SLO)
| Diagnosis
Consider causes of vasculitis:
Rabies or other vaccines?
Tick borne disease?
Drugs?
Biopsy is NOT recommended
72
Symmetrical Lupoid Onychodystrophy (SLO)
| Treatment (3 aspects)
Treat Secondary infections: Deep infection that will have to be treated for 6-8 weeks. Also do Chlorhexidine foot soaks
Pentoxifylline:
6-8 weeks to work
Long term treatment
No improvement add Doxy
Trim nails; keep them short
Nails will never be normal again
73
```
Erythema Multiforme (KNOW)
What is it?
```
NOT a diagnosis
A reaction pattern described by pathologists on histopathology:
Epidermal/keratinocyte apoptosis with lymphocytic satellitosis
74
Erythema Multiforme
| Pathogenesis
Unknown
T lymphocytes infiltration and activation -> keratinocyte apoptosis
Many triggers
75
Erythema Multiforme
| Triggers (5)
```
Drug reactions
Food Allergies
Neoplasia
Infectious (parvo)
Idiopathic (old dog EM)
```
76
Erythema Multiforme
| Drug Triggers
Antibiotics:
Sulfa, cephalosporines
Phenobarbital (hard to discontinue)
Levothyroxine
Many more but these are the common ones
77
Erythema Multiforme
| Clinical Signs
```
Acute onset
May affect skin and mucus membranes
Erythematous
Target lesions
Bullae/vesicles
Crust; plaque-like
```
78
Erythema Multiforme
| DfDx
Pemphigus vulgaris (rare and patient would be systemically ill)
Cutaneous lymphoma
Thermal burn
79
Erythema Multiforme
| Diagnosis
Biopsy (multiple):
Mark where you take it from
Epidermal/keratinocyte apoptosis with lymphocytic satellitosis
Lymphocytes surrounding keratinocytes
80
Erythema Multiforme
| Treatment
```
Address underlying cause:
Drugs
Food allergy
Screen for neoplasia
Cyclosporine?
Prednisone?
```
