|
|
(26 intermediate revisions by 2 users not shown) |
Line 1: |
Line 1: |
− | {{review}}
| + | #REDIRECT[[:Category:Integumentary System - Immunologic Pathology]] |
− | | |
− | {{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
| |