Derm Path 3 ()

• Which hypersensitivity is the "classic allergic reaction" and is mediated by IgE

  Type I
• Which hypersensitivity is IgG-mediated and cytotoxic?

  Type II
• Which hypersensitivity is caused be immune complexes and complement activation?

  Type III
• Which hypersensitivity is cell-mediated (cytotoxic T-cells)?

  Type IV
• Define pruritus vs. atopy/atopic dermatitis

  Pruritus = an irritating sensation that makes an animal want to scratch, or "itchy skin". This is a verynon-specific clinical sign.

  Atopy = one of many causes of pruritus. Atopy is aheritable tendency to developIgE-mediated allergic reactions(type 1 hypersensitivity).

  Atopic dermatitis = inflammation of the skin due to atopy (IgE immune-mediated reaction)
• Urticaria (hives) are an example of a type ______ hypersensitivity


  I
• Culicoides hypersensitivity in horses is an example of type _____ and _____ hypersensitivity

  I, IV

  
• A mosquito bite is an example of a type ____ hypersensitivity

  I
• Allergic contact dermatitis is an example of a type ____ sensitivity (sensitized T cells)

  IV
• Pemphigus foliaceus vs. Pemphigus vulgaris:

  
  

  Which is most common?

  Which is most severe?

  Pemphigus foliaceus is most common and least severe.

  Pemphigus vulagris is least common and most severe.
• Pemphigus foliaceus vs. Pemphigus vulgaris:

  
  

  Autoantibodies are produced against which layer?

  PF - autoantibodies to desmosomes in upper layers

  PV - autoantibodies to desmosomes in deeper layer
• Pemphigus foliaceus vs. Pemphigus vulgaris:

  
  

  What is a common histologic finding?

  Acantholytic keratinocytes (live keratinocytes that are detached from the rest of the cells)
• Pemphigus foliaceus vs. Pemphigus vulgaris:

  
  

  They are both a type _______ hypersensitivity

  II
• Pemphigus foliaceus vs. Pemphigus vulgaris:

  
  

  How do the gross lesions differ?

  PF - pustules, erosions, crusts. Bilateral and symmetrical.

  
  

  PV - Fragile vesicles and bullae in the epidermis and oral mucosa.
• Lupus erythematosus is a type _____ hypersensitivity

  III

  
• You are examining a dog that you suspect has lupus erythematosus based on the clinical signs and lesions. What could you expect to find on histo?

  Lymphoplasmacytic interface dermatitis

  
• Compare and contrast erythema multiforme and toxic epidermal necrolysis

  Erythema multiforme:

  - Histo: keratinocyte apoptosis + lymphocytes

  - More mild than TEN

  
  

  Toxic epidermal necrolysis (TEN):

  - Histo: keratinocyte apoptosis + lymphocytes (just more widespread)

  - Much more severe and life-threatening

  - > 30% epidermal detachment/ulceration
• Which is a more likely Dx? Erythema multiforme or toxic epidermal necrolysis (TEN)?

  TEN is more likely due to widespread and severe epidermal detachment/ulceration

  
• Describe the pathogenesis for rabies vax induced alopecia in dogs

  Type III HS suspected:Antibody-antigen complexes lodge in blood vessels ->vasculitis-> ischemia -> follicular atrophy ->alopecia

  
• What are the three forms of the feline eosinophilic granuloma complex?

  - Feline eosinophilic granuloma

  - Feline eosinophilic plaque

  - Indolent ulcer
• Which of the three forms of the feline eosinophilic granuloma complex is the ONLY ONE that is pruritic?

  Feline eosinophilic plaque
• Where do feline eosinophilic plaques tend to occur?

  Ventral abdomen, medial thighs, perineum
• Give a Ddx

  Feline eosinophilic plaques

  
• Where do feline eosinophilic granulomas tend to occur?

  Can be cutaneous, mucocutaneous, or oral
• Where do indolent ulcers (rodent ulcers) tend to occur?

  Upper lip
• Give two Ddx for this non-pruritic lesion

  - Indolent ulcer

  - Squamous cell carcinoma

  
• Describe the common clinical presentation for endocrine dermatopathies

  "Clinical features of many endocrine dermatoses include dry, coarse, brittle, dull, easily epilated haircoat that fails to regrow after clipping; hypotrichosis and hyperpigmentation; and alopecia that is frequently bilateral and symmetrical"
• What is a unique clinical feature of hypothyroidism?

  Myxedema (swelling of the face causing a "tragic expression)

  
• What is a unique feature of hyperadrenocorticism (Cushing's)?

  Calcinosis cutis
• Identify the histologic feature shown here

  Calcinosis cutis

  
• What is a histologic feature of hyperestrogenism?

  Telogen (resting) hair follicles dominate

  
• What is a clinical/gross feature of hyperestrogenism?

  Symmetric hypotrichosis or alopecia that is progressive from caudal (perineum) to cranial
• Alopecia X (also called growth hormone/castration-responsive dermatosis) is an disease seen in plush-coated Nordic breeds. What does the thyroid and adrenal function look like in these patients?


  Normal thyroid function

  Normal adrenal function

  
  

  *Note: Helps us rule out hypothyroidism and Cushing's

  
• Which histo lesion is characteristic for canine recurrent flank alopecia?

  Non-inflammatory,non-pruritic, follicular atrophy