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Dermatology > Immune Mediated Dermatoses > Flashcards

Immune Mediated Dermatoses Flashcards

1
Q

What do immune-mediated diseases imply vs autoimmune diseases?

A
  • Implies a foreign antigen (protein) that triggers an immunological reaction
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2
Q

Antigens that can trigger an immunological reaction

A
  • Drugs!
  • Bacteria
  • Viruses
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3
Q

Severity of immune-mediated diseases

A
  • Often very acute and very severe
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4
Q

What’s important for immune-mediated diseases?

A
  • Thorough history is extremely important
  • Travel history
  • Consider tickborne diseases
  • Drug hx
  • vaccine history
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5
Q

Vasculitis

A
  • Characterized by inflammation and destruction of blood vessels, resulting in ischemic necrosis
  • Poor blood supply to the skin leads to ischemic dermatopathy
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6
Q

Pathophysiology of Vasculitis

A
  • Type III hypersensitivity
  • Antigen-antibody complex lodges into the endothelium of blood vessels leading to a complement cascade (C1, C5a, C3b)
  • C5a recruits neutrophils leading to release of lysozomal enzymes
  • These enzymes recruit macrophages and mast cells and lead to a lot of damage
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7
Q

Triggering causes of vasculitis

A
  • Idiopathic (up to 50%)
  • Infectious
  • Drugs
  • Immune-mediated
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8
Q

Who gets idiopathic vasculitis?

A

Jack Russell Terriers

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9
Q

Infectious causes of vasculitis

A
  • Bacterial
  • Viral (Parvo, Coronavirus)
  • Protozoal (Leishmania, Sarcocystis)
  • Rickettsial (RMSF, Ehrlichia, Babesia)
  • Fungal
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10
Q

Drugs that can lead to vasculitis

A
  • Injection of foreign proteins (Rabies vax!)***
  • Antibiotics
  • Ivermectin
  • Itraconazole
  • Fenbendazole
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11
Q

Immune-mediated causes of vasculitis

A
  • Systemic lupus erythematosus

- Rheumatoid arthritis

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12
Q

What causes Rabies vaccine induced vasculitis?

A
  • Detected in blood vessels and epithelium of hair follicles
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13
Q

Breeds at risk for Rabies Vaccine induced vasculitis?

A
  • Poodles
  • Silky terrier
  • Pekingese
  • Maltese
  • Bichon frise
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14
Q

Initial clinical signs of Rabies vaccine induced vasculitis

A
  • Circular area of alopecia at the site of the vaccine
  • Looks like dermatophytosis but no active inflammation
  • Signs can be seen 2-8 months after vaccination
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15
Q

How long can signs occur after vaccination for rabies vax induced vasculitis?

A
  • 2-8 months after
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16
Q

Differentials for ear tip vasculitis

A
  • Pemphigus

- Ectoparasites like Scabies or Notoedres (but these are very itchy)

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17
Q

Appearance of ear tip vasculitis

A
  • Exposure of cartilage and shaking (if cartilage is exposed, it’s painful)
  • Characteristic notching
  • Only affects the inner ear
  • Clinical diagnosis
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18
Q

What to do if you suspect rabies is the triggering cause of vasculitis?

A
  • DO NOT vaccinate

- Consider rabies antibody titers

19
Q

Example history for a dog with vaccine induced vasculitis

A
  • Chief complaint: non-pruritic, progressive hair loss
  • History of discoloration on ear tips for last 3 years
  • Non-pruritic alopecia of right axilla/chest and digits starting in April 2010
  • No meds
  • Vaccinated in Feb 2010 in the right shoulder area
  • In June, skin scrapes were neg for demodex
  • Treated with ketoconazole for possible yeast infection
  • No improvement noted by owner
  • ruled out tick borne disease
  • After thorough drug and vaccine history, clinical diagnosis made
  • Biopsy - seeing active vasculitis is rare to difficult but other changes could support
20
Q

Treatment for Rabies vaccine induced vasculitis

A
  • Pentoxyfilline

- Doxycycline/niacinamide

21
Q

Pentoxifylline type of drug

A
  • Methylxanthine
22
Q

Pentoxyfylline MOA

A
  • Potent hemorrheologic and anti-inflammatory properties
  • Improves microcirculation
  • Inhibits cytokines (IL-1, IL-6, TNFa)
  • Inhibits leukocyte and platelet adhesion to endothelial cells
23
Q

How long can it take for pentoxifylline to become effective?

A
  • Approximately 6-8 weeks
24
Q

Doxycycline/niacinamide MOA

A
  • Inhibits matrix metalloproteases

- Anti-inflammatory properties

25
Q

How long can it take for doxycycline/niacinamide to be effective?

A
  • 6-8 weeks
26
Q

How does Dr. Mel use doxycycline/niacinamide for vasculitis treatment?

A
  • Used with pentoifylline if pentoxy isn’t successful

- He doesn’t use this right away

27
Q

What might you consider for very severe and non-responsive cases of vasculitis

A
  • Amputation of ear tips in very severe cases
28
Q

Symmetrical lupoid onychodystrophy - what is it? How common? Etiology?

A
  • Acute onset nail loss
  • Uncommon claw disease
  • Unknown etiology
  • Suspected to have a vasculitic, immune-mediated component
29
Q

Clinical signs of symmetrical lupoid onychodystrophy?

A
  • Acute onset of nail loss
  • May affect only a few but will progress
  • Can be painful
  • Dogs may lick
  • SEparation of nails from quick
  • Splitting of claws
  • Secondary digit infections?
30
Q

What is the word for separation of nails from the quick?

A
  • Onycholysis
31
Q

What is the word for splitting of the claws?

A
  • Onychoschizia
32
Q

Diagnosis of symmetrical lupoid onychodystrophy

A
  • Clinical
  • Consider causes of vasculitis (rabies or other vaccines; tick borne; drugs)
  • Biopsies not recommended
33
Q

Treatment of symmetrical lupoid onychodystrophy

A
  • Treat secondary infections (mal odor? swollen digits? would it be superficial or deep?)
  • Treat for 6-8 weeks
  • WHich antibiotic? (ideally culture!)
  • Pentoxyifylline
  • Doxy/niacinamide in addition if not responding
  • Keep claws short
34
Q

What is an important part of managing symmetrical lupoid onychodystrophy?

A
  • Keep claws short, as they will regrow abnormal
  • Goal is abnormally normal
  • Filing or dremmel are helpful
35
Q

What is erythema multiforme?

A
  • Reaction pattern described by pathologists on histopathology
  • Epidermal/keratinocyte apoptosis with lymphocytic satellitosis
36
Q

Pathogenesis of erythema multiforme

A
  • Unknown
  • T cell infiltration and activation –> keratinocyte apoptosis
  • Many possible triggers
37
Q

Reported triggers of erythema multiforme

A
  • Drug reactions
  • Food allergies
  • Neoplasia
  • Infections like parvo
  • Idiopathic (old dog EM)
38
Q

Drugs that can trigger erythema multiforme

A
  • Antibiotics (sulfa, cephalosporins, MANY more)

- Other drugs (phenobarbital, levothyroxine, many more)

39
Q

Clinical signs of erythema multiforme

A
  • Acute
  • May affect skin and mucous membranes
  • ERythematous macules
  • Target lesions
  • Bullae/vesicles
  • Crust
  • More plaque like crustin g
40
Q

Differentials for erythema multiforme

A
  • Pemphigus vulgaris
  • Cutaneous lymphoma
  • Thermal burn
41
Q

Diagnosis of erythema multiforme

A
  • Biopsy!
42
Q

What does biopsy show with erythema multiforme?

A
  • Epidermal/keratinocyte apoptosis with lymphocyte satellitosis
43
Q

Treatment of erythema multiforme?

A
  • Look for underlying cause
  • Drug history
  • Food allergy!
  • Neoplasia screen
  • Cyclosporine? Prednisone?
44
Q

What should you always think with itching/licking paws/overgrooming?

A
  • ALLERGIES UNTIL PROVEN OTHERWISE

Dermatology (15 decks)

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