Difference between revisions of "Skin Immunologic - Pathology"

From WikiVet English
Jump to navigation Jump to search
(26 intermediate revisions by 2 users not shown)
Line 1: Line 1:
−
#REDIRECT[[:Category:Integumentary System - Immunologic Pathology]]
+
{{review}}
 +
 
 +
{{toplink
 +
|backcolour = FFCCCC
 +
|linkpage =Integumentary System - Pathology
 +
|linktext =Integumentary System
 +
|maplink = Integumentary System (Content Map) - Pathology
 +
|pagetype =Pathology
 +
}}
 +
<br>
 +
 
 +
==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 - WikiBlood|mast cells]] and [[Basophils - WikiBlood|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:
 +
**[[Skin Immunologic - Pathology#Atopy|Atopic dermatitis]]
 +
**[[Skin Glossary - Pathology|Urticaria]]
 +
**Angioedema
 +
**Fly bite hypersensitivity
 +
**Gastrointestinal parasites
 +
**Food
 +
*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 - WikiBlood#Complement Fixation Pathways|complement fixation]] -> cellular damage
 +
*In skin - circulating antibody to proteins of desmosomes in intercellular areas along basement membranes at epidermal-dermal junction
 +
*Includes:
 +
**[[Skin Immunologic - Pathology#Pemphigus|Pemphigus]]
 +
**[[Skin Immunologic - Pathology#Bullous pemphigoid|Bullous pemphigoid]]
 +
 
 +
===Type III reactions===
 +
*[[Complement - WikiBlood#Complement Fixation Pathways|Complement fixing]] immune complexes
 +
*IgG or IgM
 +
*Complexes deposit in tissue -> fix complement -> cytokines and othe factors attrack neutrophils -> release lysosomal enzymes, activation of complement and coagulation, platelet aggregation -> tissue damage
 +
*Immune complex vasculitis -> [[General Pathology - Haemorrhage#Purpura haemorrhagica|purpura haemorrhagica]]
 +
*Includes:
 +
**[[Skin Immunologic - Pathology#Lupus erythematosus|Systemic lupus erythematosus]]
 +
**[[Skin Immunologic - Pathology#Dermatomyositis|Canine dermatomyositis]]
 +
 
 +
===Type IV reactions===
 +
*Delayed hypersensitivity
 +
*Haptens bind to carrier proteins (mainly epidermal)
 +
*Mediated by sensitised [[T cell differentiation - WikiBlood|T-cells]] -> release cytokines +/- recruit lymphocytes
 +
*Used in diagnosis of tuberculosis, histoplasmosis and coccidiomycosis
 +
*Perivascular mononuclear cell accumulation
 +
 
 +
==Hypersensitivity reactions==
 +
 
 +
===Allergic contact dermatitis===
 +
 
 +
*Usually involves [[Skin Immunologic - Pathology#Type IV reactions|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 - WikiBlood|eosinophils]]
 +
 
 +
===Atopy===
 +
 
 +
*Involves [[Skin Immunologic - Pathology#Type I reactions|Type I reaction]]
 +
*Mainly causes pruritus
 +
*Dogs - face rubbing and foot licking; secondary [[Bacterial skin infections - Pathology#Pyoderma|pyoderma]] or [[Skin Other#Secondary seborrhea|seborrhea]]
 +
*Cats - facial, ear or generalised pruritus, miliary dermatitis, [[Skin Other - Pathology#Eosinophilic granuloma|eosinophilic granuloma complex]], symmetric alopecia
 +
*Horses - pruritic hea, pinnae, ventrum, legs, tailhead or recurrent [[Skin Glossary - Pathology|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
 +
 
 +
===Culicoides hypersensitivity===
 +
 
 +
*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
 +
*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 [[Skin Other - Pathology#Eosinophilic granuloma|eosinophilic granulomas]]
 +
 
 +
===Flea bite 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
 +
*Secondary trauma is self-inflicted
 +
*Grossly:
 +
**Papular dermatitis
 +
**Secondary excoriations
 +
**Alopecic nodule if chronic
 +
*Microscopically:
 +
**Hyperplastic superficial perivascular dermatitis
 +
**Oedema, [[Mast Cells - WikiBlood|mast cells]], [[Basophils - WikiBlood|basophils]], [[Eosinophils - WikiBlood|eosinophils]], [[Lymphocytes - WikiBlood|lymphocytes]], histiocytes
 +
**Fibropruritic nodules covered by hyperplastic epidermis
 +
 
 +
==Autoimmune reactions==
 +
 
 +
===Bullous pemphigoid===
 +
 
 +
*Dogs and horses
 +
*Involves oral cavity, mucocutaneous junctions, groin and axilla
 +
*Subepidermal vesicles and bullae
 +
*Antibodies bound to basement membrane
 +
*Grossly:
 +
**Similar to [[Skin Immunologic - Pathology#Pemphigus|Pemphigus vulgaris]]
 +
*Microscopically:
 +
**Bullae containing fibrin, [[Neutrophils - WikiBlood|neutrophils]] or [[Eosinophils - WikiBlood|eosinophils]]
 +
**Basement membrane forms floor of bullae and roof is lined with basal cells
 +
*Bullae may rupture -> ulcers
 +
 
 +
===Dermatomyositis===
 +
*See also [[Muscles Developmental - Pathology#Canine dermatomyositis|Canine dermatomyositis]]
 +
*Affects puppies of collies and shetland sheepdogs from 8 weeks of age
 +
*Lesions - vesiculating dermatitis
 +
**Face, lips, external ears, later distal extremities
 +
*Microscopically: interface dermatitis and basal cell degeneration of epidermis and follicular wall, atrophy of follicles, epidermal vesicles and pustules, dermal scarring
 +
 
 +
===Lupus erythematosus===
 +
 
 +
*'''Systemic (SLE)'''
 +
**Multiple organs involved
 +
**Cats, dogs, horses
 +
**Immune dysregulation:
 +
***Damaged T-cell suppressor function, either primary deficiency or antibody mediated
 +
***Cytokine dysregulation
 +
***Resulting B-cell hyperactivity -> antibodies to self antigens -> antigen-antibody complexes deposited in various tissues -> Type III hypersensitivity
 +
**Lesions localised or generalised
 +
**Erythema, alopecia, depigmentation, crusting and scaling, ulceration
 +
**Microscopically: lymphohistiocytic interface dermatitis, thickened basement membrane, vasculitis, subepidermal vesicles, basal cell degeneration
 +
*'''Discoid'''
 +
**Milder variant of systemic
 +
**Depigmentation, erythema, scaling, erosions, ulceration, crusting
 +
**Usually involves nasal planum, dorsum of muzzle, occasionally pinnae, lips, oral mucosa or periocular area
 +
**Microscopically: lichenoid interface dermatitis, often with lymphocytes, plasma cells, basal cell degeneration, loss of pigment
 +
 
 +
===Pemphigus===
 +
 
 +
*Blistering diseases
 +
*Autoantibodies bind to desmosomal proteins -> cell adhesion disrupted -> vesicles
 +
*Types:
 +
**'''Pemphigus vulgaris'''
 +
***Rare, severe form
 +
***Cats and dogs
 +
***Vesicles or bullae -> erosions and ulcers
 +
***Involves oral cavity, mucocutaneous junctions and skin
 +
***Microscopically:
 +
****Suprabasilar vesiculation and row of basal cells adhering to basement membrane
 +
****Superficial perivascular dermatitis
 +
**'''Pemphigus vegetans'''
 +
***Rare
 +
***Dogs
 +
***Involves the trunk
 +
***Mild version of P. vulgaris
 +
***Vesicopustular dermatitis + epidermal hyperplasia -> papillomatous formations
 +
**'''Pemphigus foliaceus'''
 +
***More common
 +
***Cats, dogs, horses, goats
 +
***Localised lesions or generalised
 +
***Symmetrical vesicular or pustular dermatitis, crusts, scales, alopecia
 +
***Microscopically:
 +
****Acantholytic cells
 +
****Subcorneal or intragranular pustules
 +
****In third of equine or canine cases [[Eosinophils - WikiBlood|eosinophils]] are predominant
 +
**'''Pemphigus erythematosus'''
 +
***Cats and dogs
 +
***Mild form of P. foliaceus
 +
***Usually involves only face and external ears

Revision as of 12:11, 30 October 2008

 This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing.


WikiPathWikiPath Banner.png
()Map INTEGUMENTARY SYSTEM (Map)



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

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

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

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

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:

Autoimmune reactions

Bullous pemphigoid

  • Dogs and horses
  • Involves oral cavity, mucocutaneous junctions, groin and axilla
  • Subepidermal vesicles and bullae
  • Antibodies bound to basement membrane
  • Grossly:
  • Microscopically:
    • Bullae containing fibrin, neutrophils or eosinophils
    • Basement membrane forms floor of bullae and roof is lined with basal cells
  • Bullae may rupture -> ulcers

Dermatomyositis

  • See also Canine dermatomyositis
  • Affects puppies of collies and shetland sheepdogs from 8 weeks of age
  • Lesions - vesiculating dermatitis
    • Face, lips, external ears, later distal extremities
  • Microscopically: interface dermatitis and basal cell degeneration of epidermis and follicular wall, atrophy of follicles, epidermal vesicles and pustules, dermal scarring

Lupus erythematosus

  • Systemic (SLE)
    • Multiple organs involved
    • Cats, dogs, horses
    • Immune dysregulation:
      • Damaged T-cell suppressor function, either primary deficiency or antibody mediated
      • Cytokine dysregulation
      • Resulting B-cell hyperactivity -> antibodies to self antigens -> antigen-antibody complexes deposited in various tissues -> Type III hypersensitivity
    • Lesions localised or generalised
    • Erythema, alopecia, depigmentation, crusting and scaling, ulceration
    • Microscopically: lymphohistiocytic interface dermatitis, thickened basement membrane, vasculitis, subepidermal vesicles, basal cell degeneration
  • Discoid
    • Milder variant of systemic
    • Depigmentation, erythema, scaling, erosions, ulceration, crusting
    • Usually involves nasal planum, dorsum of muzzle, occasionally pinnae, lips, oral mucosa or periocular area
    • Microscopically: lichenoid interface dermatitis, often with lymphocytes, plasma cells, basal cell degeneration, loss of pigment

Pemphigus

  • Blistering diseases
  • Autoantibodies bind to desmosomal proteins -> cell adhesion disrupted -> vesicles
  • Types:
    • Pemphigus vulgaris
      • Rare, severe form
      • Cats and dogs
      • Vesicles or bullae -> erosions and ulcers
      • Involves oral cavity, mucocutaneous junctions and skin
      • Microscopically:
        • Suprabasilar vesiculation and row of basal cells adhering to basement membrane
        • Superficial perivascular dermatitis
    • Pemphigus vegetans
      • Rare
      • Dogs
      • Involves the trunk
      • Mild version of P. vulgaris
      • Vesicopustular dermatitis + epidermal hyperplasia -> papillomatous formations
    • Pemphigus foliaceus
      • More common
      • Cats, dogs, horses, goats
      • Localised lesions or generalised
      • Symmetrical vesicular or pustular dermatitis, crusts, scales, alopecia
      • Microscopically:
        • Acantholytic cells
        • Subcorneal or intragranular pustules
        • In third of equine or canine cases eosinophils are predominant
    • Pemphigus erythematosus
      • Cats and dogs
      • Mild form of P. foliaceus
      • Usually involves only face and external ears
Retrieved from "https://en.wikivet.net/index.php?title=Skin_Immunologic_-_Pathology&oldid=40936"