Difference between revisions of "Skin Immunologic - Pathology"

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(New page: {{toplink |backcolour = FFCCCC |linkpage =Integumentary System - Pathology |linktext =Integumentary System |maplink = Integumentary System (Content Map) - Pathology |pagetype =Pathology }...)
 
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*Immediate reaction
 
*Immediate reaction
 
*Includes:
 
*Includes:
−
**[[Skin - immunologic#Atopy|Atopic dermatitis]]
+
**[[Skin Immunologic - Pathology#Atopy|Atopic dermatitis]]
 
**[[Skin Glossary - Pathology|Urticaria]]
 
**[[Skin Glossary - Pathology|Urticaria]]
 
**Angioedema
 
**Angioedema
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*In skin - circulating antibody to proteins of desmosomes in intercellular areas along basement membranes at epidermal-dermal junction
 
*In skin - circulating antibody to proteins of desmosomes in intercellular areas along basement membranes at epidermal-dermal junction
 
*Includes:
 
*Includes:
−
**[[Skin - immunologic#Pemphigus|Pemphigus]]
+
**[[Skin Immunologic - Pathology#Pemphigus|Pemphigus]]
−
**[[Skin - immunologic#Bullous pemphigoid|Bullous pemphigoid]]
+
**[[Skin Immunologic - Pathology#Bullous pemphigoid|Bullous pemphigoid]]
  
 
===Type III reactions===
 
===Type III reactions===
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*Immune complex vasculitis -> [[General Pathology - Haemorrhage#Purpura haemorrhagica|purpura haemorrhagica]]
 
*Immune complex vasculitis -> [[General Pathology - Haemorrhage#Purpura haemorrhagica|purpura haemorrhagica]]
 
*Includes:
 
*Includes:
−
**[[Skin - immunologic#Lupus erythematosus|Systemic lupus erythematosus]]
+
**[[Skin Immunologic - Pathology#Lupus erythematosus|Systemic lupus erythematosus]]
−
**[[Skin - immunologic#Dermatomyositis|Canine dermatomyositis]]
+
**[[Skin Immunologic - Pathology#Dermatomyositis|Canine dermatomyositis]]
  
 
===Type IV reactions===
 
===Type IV reactions===
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===Atopy===
 
===Atopy===
  
−
*Involves [[Skin - immunologic#Type I reactions|Type I reaction]]
+
*Involves [[Skin Immunologic - Pathology#Type I reactions|Type I reaction]]
 
*Mainly causes pruritus
 
*Mainly causes pruritus
 
*Dogs - face rubbing and foot licking; secondary [[Bacterial skin infections - Pathology#Pyoderma|pyoderma]] or seborrhea
 
*Dogs - face rubbing and foot licking; secondary [[Bacterial skin infections - Pathology#Pyoderma|pyoderma]] or seborrhea
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===Flea bite hypersensitivity===
 
===Flea bite hypersensitivity===
  
−
*Usually involves [[Skin - immunologic#Type I reactions|Type I reaction]] and [[Skin - immunologic#Type IV reactions|Type IV reaction]] and cutaneous basophil hypersensitivity
+
*Usually involves [[Skin Immunologic - Pathology#Type I reactions|Type I reaction]] and [[Skin Immunologic - Pathology#Type IV reactions|Type IV reaction]] and cutaneous basophil hypersensitivity
 
*Mainly dorsolumbosacral area involved, abdomen, caudomedial thighs, flanks, neck of cats
 
*Mainly dorsolumbosacral area involved, abdomen, caudomedial thighs, flanks, neck of cats
 
*Secondary trauma is self-inflicted
 
*Secondary trauma is self-inflicted
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===Culicoides hypersensitivity===
 
===Culicoides hypersensitivity===
  
−
*Usually involves [[Skin - immunologic#Type I reactions|Type I reaction]] and [[Skin - immunologic#Type IV reactions|Type IV reaction]]  due to salivary antigens of ''Culicoides'' sp.
+
*Usually involves [[Skin Immunologic - Pathology#Type I reactions|Type I reaction]] and [[Skin Immunologic - Pathology#Type IV reactions|Type IV reaction]]  due to salivary antigens of ''Culicoides'' sp.
 
*May be seasonally recurring or continuous depending on climate
 
*May be seasonally recurring or continuous depending on climate
 
*Grossly:
 
*Grossly:
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===Allergic contact dermatitis===
 
===Allergic contact dermatitis===
  
−
*Usually involves [[Skin - immunologic#Type IV reactions|Type IV reaction]]
+
*Usually involves [[Skin Immunologic - Pathology#Type IV reactions|Type IV reaction]]
 
*Pruritic lesions with self-inflicted trauma
 
*Pruritic lesions with self-inflicted trauma
 
*At areas in contact with allergen
 
*At areas in contact with allergen

Revision as of 12:33, 31 July 2008

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General

  • Classification:
    • Hypersensitivity - response to normally harmless substances
    • Auto-immune - antobodies or T-cells reactive against self-antigens
  • Mostly involves mixture of types described below

Type I reactions

  • Mediated by pharmacologically active substances from mast cells and basophils
    • Due to antigen-antibody (usually IgE) binding to receptors on those cells
  • Substances include histamine, serotonin, leukotriens, prostaglandins
  • Can be systemic or local
  • Skin becomes pruritic, raised erythematous borders of wheals
  • Immediate reaction
  • Includes:
  • Microscopically:
    • Capillary dilation, oedema, mast cell degranulation, eosinophil infiltration

Type II reactions

  • Cytotoxic reaction
  • IgG and IgM interaction with antigens bound to cellular membranes
  • Often involves complement fixation -> cellular damage
  • In skin - circulating antibody to proteins of desmosomes in intercellular areas along basement membranes at epidermal-dermal junction
  • Includes:

Type III reactions

Type IV reactions

  • Delayed hypersensitivity
  • Haptens bind to carrier proteins (mainly epidermal)
  • Mediated by sensitised T-cells -> release cytokines +/- recruit lymphocytes
  • Used in diagnosis of tuberculosis, histoplasmosis and coccidiomycosis
  • Perivascular mononuclear cell accumulation

Hypersensitivity reactions

Atopy

  • Involves Type I reaction
  • Mainly causes pruritus
  • Dogs - face rubbing and foot licking; secondary pyoderma or seborrhea
  • Cats - facial, ear or generalised pruritus, miliary dermatitis, eosinophilic granuloma complex, symmetric alopecia
  • Horses - pruritic hea, pinnae, ventrum, legs, tailhead or recurrent urticaria
  • Lesions generally due to self-trauma
  • Microscopically:
    • Hyperplastic superficial perivascular dermatitis
    • Mast cells, eosinophils, nonmetachromatic mononuclear cells
    • Perivascular inflammation may be involved especially in horses

Flea bite hypersensitivity

  • Usually involves Type I reaction and Type IV reaction and cutaneous basophil hypersensitivity
  • Mainly dorsolumbosacral area involved, abdomen, caudomedial thighs, flanks, neck of cats
  • Secondary trauma is self-inflicted
  • Grossly:
    • Papular dermatitis
    • Secondary excoriations
    • Alopecic nodule if chronic
  • Microscopically:

Culicoides hypersensitivity

  • Usually involves Type I reaction and Type IV reaction due to salivary antigens of Culicoides sp.
  • May be seasonally recurring or continuous depending on climate
  • Grossly:
    • Papules, crusts, alopecia, excoriations, lichenification
  • Microscopically:
    • Superficial and dep perivascular dermatitis
    • Many eosinophils
    • Epidermal hyperplasia
    • Hyperkeratosis
    • Dermal fibrosis
    • Possibly eosinophilic folliculitis, intraepidermal pustules and eosinophilic granulomas

Allergic contact dermatitis

  • Usually involves Type IV reaction
  • Pruritic lesions with self-inflicted trauma
  • At areas in contact with allergen
  • Grossly:
    • Erythema, papules, +/- vesicles, exudation -> crusts
    • If chronic, lichenification, hyperpigmentation, alopecia
  • Microscopically:
    • Spongiotic superficial perivascular dermatitis
    • Mononuclear cells
    • If chronic, epidermal hyperplasia
    • May involve eosinophils

Autoimmune reactions

BS-to-finish

Dermatomyositis

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