Difference between revisions of "Skin Environmental - Pathology"
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− | # | + | ==Chemical damage== |
+ | ===[[Contact Dermatitis]]=== | ||
+ | |||
+ | ===[[Ergot Poisoning]]=== | ||
+ | |||
+ | |||
+ | |||
+ | ===[[Fescue Poisoning]]=== | ||
+ | |||
+ | |||
+ | ===[[Selenium Poisoning]]=== | ||
+ | |||
+ | |||
+ | ==Physical damage== | ||
+ | |||
+ | ===[[Acral Lick Dermatitis]]=== | ||
+ | |||
+ | ===[[Callus]]=== | ||
+ | |||
+ | ===[[Feline Psychogenic Alopecia]]=== | ||
+ | |||
+ | |||
+ | |||
+ | ===Injection site reaction=== | ||
+ | *May be caused by subcutaneous injections | ||
+ | *Granulomatous nodules form with central necrotic and foreign material | ||
+ | *Macrophages and multinucleated giant cells around the centre | ||
+ | *Surrounded by granulation tissue, perivascular lymphocytes that may form lymphoid follicles, eosinophils | ||
+ | *Cats may develop fibrosarcomas secondary to vaccination | ||
+ | *Dogs, especially poodles, may develop lymphoplasmacytic panniculitis and perivasculitis, vasculitis and follicular atrophy secondary to killed rabies vaccine | ||
+ | |||
+ | |||
+ | [[Category:Integumentary System - Physical Damage]] | ||
+ | |||
+ | |||
+ | ===Intertrigo=== | ||
+ | *Also called '''skin fold dermatitis''' | ||
+ | *Develops due to irritation and bacteria in areas of skin friction and moisture (tears, saliva, glandular secretions, urine) | ||
+ | *Areas affected are commonly facial fold in brachycephalic breeds, [[Lips|lip]] fold, body fold, vulvular fold (obese females), tail fold (corkscrew tails) | ||
+ | *Cows with large, pendolous udder may become affected in area between thigh and udder | ||
+ | **In severe cases, skin and subcutis may slough | ||
+ | |||
+ | [[Category:Integumentary System - Physical Damage]] | ||
+ | |||
+ | |||
+ | ===Pyotraumatic dermatitis=== | ||
+ | *Also called '''acute moist dermatitis''' or ''''hot spot'''' | ||
+ | *Common in dogs, especially self-inflicted due to pain and itching | ||
+ | *Usual causes: [[Skin Immunologic - Pathology|allergies]], irritants, matted hair, [[Parasitic skin infections - Pathology|parasites]] | ||
+ | *Lesions tend to be worse in hot and humid weather | ||
+ | *Grossly: | ||
+ | **Hairless, red and moist lesion | ||
+ | **Fluid exudate | ||
+ | **Edges are circumscribed and red | ||
+ | *Microscopically: | ||
+ | **Superficial erosive to ulcerative exudative dermatitis | ||
+ | **May be deeper suppurative folliculitis | ||
+ | |||
+ | [[Category:Integumentary System - Physical Damage]] | ||
+ | |||
+ | |||
+ | ===Radiation damage=== | ||
+ | *Cells sensitive to radiation include [[Skin Glossary - Pathology|anagen]] hair follicles, germinal basal cells, melanocytes and endothelial cells | ||
+ | *Early changes: | ||
+ | **Erythema, epidermal blisters and oedema, erosions and ulceration | ||
+ | **Healed by scarring, hyperpigmentation with lower doses and hypopigmentation with higher doses | ||
+ | **Temporary or permanent alopecia | ||
+ | *Chronic changes: | ||
+ | **Scarring, altered pigmentation, alopecia | ||
+ | **Epidermal and adnexal atrophy | ||
+ | **Degeneration of vascular and elastic tissue | ||
+ | **Fibrosis of dermal and subcutaneous tissue | ||
+ | **Ulceration | ||
+ | **In severe damage, squamous cell carcinoma may develop | ||
+ | |||
+ | [[Category:Integumentary System - Physical Damage]] | ||
+ | |||
+ | |||
+ | ===Low temperature damage=== | ||
+ | *Prolonged cold can cause ice crystal formation and vascular injury resultic in damage to tissue due to increased intracellular salt concentration | ||
+ | *Slow chilling can cause vasoconstriction, cellular damage -> secondary vasodilation and increased permeability -> oedema | ||
+ | *Severe and persistent cold causes vasoconstriction, increase in blood viscosity and tissue anoxia | ||
+ | *Lesions may occur in wet or hypoglycaemic neonates or animals recently moved from warm to cold environment | ||
+ | *Areas affected are extremities | ||
+ | *Lesions consist of [[Necrosis - Pathology#Gangrene|gangrene]] and necrotic tissue | ||
+ | |||
+ | |||
+ | [[Category:Integumentary System - Physical Damage]] | ||
+ | |||
+ | |||
+ | ===High temperature damage=== | ||
+ | *May result from excessive heat, liquids, flames, friction, lightning, electricity | ||
+ | *Partial or full thickness burns (first, second and third degree burns) | ||
+ | *Full thickness burns: | ||
+ | **Total destruction of skin and adnexa | ||
+ | **Has to be repaired by grafting | ||
+ | **Life threatening | ||
+ | *Partial thickness burns: | ||
+ | **Some structures preserved -> regeneration may occur | ||
+ | **Grossly: | ||
+ | ***Erythema (capillary dilation) | ||
+ | ***Oedema (increased permeability of capillaries) | ||
+ | ***Vesicles | ||
+ | **Microscopically: | ||
+ | ***[[Necrosis - Pathology#Coagulation Necrosis|Coagulation necrosis]] of epidermis | ||
+ | ***Subepidermal vesiculation | ||
+ | ***Necrosis of adnexa | ||
+ | ***Degenerated subepidermal collagen | ||
+ | ***May involve large numbers of [[Neutrophils|neutrophils]] if secondary ifection is present | ||
+ | |||
+ | |||
+ | [[Category:Integumentary System - Physical Damage]] | ||
+ | |||
+ | ==Sunlight damage== | ||
+ | *Transient erythema may develop into sunburn erythema (warmth, swelling, pain) | ||
+ | *Diffusion of inflammatory mediators (''e.g.'' cytokines) from damaged keratinocytes and endothelial cells | ||
+ | *Photooxidation of existing melanin -> pigment darkening | ||
+ | *Melanogenesis | ||
+ | *Immune responses of skin are reduced by UV light | ||
+ | |||
+ | |||
+ | [[Category:Integumentary System - Sunlight Damage]] | ||
+ | |||
+ | |||
+ | ===Solar dermatosis and neoplasia=== | ||
+ | *Caused by chronic sunlight damage | ||
+ | *Damaged tissue generates free radicals than may damage nucleis acids and proteins | ||
+ | *If damage repaired prior to mitosis - no lasting effect | ||
+ | *If mitosis occurs before repair, post-mitotic repair is prone to faults and DNA mutations may result in neoplasia | ||
+ | |||
+ | |||
+ | [[Category:Integumentary System - Sunlight Damage]] | ||
+ | |||
+ | |||
+ | ===Solar dermatitis=== | ||
+ | *Particularly in white animals and where little or no hair is present | ||
+ | *Grossly: | ||
+ | **[[Skin Glossary - Pathology|Erythema, scaling and crusting]] | ||
+ | **-> Wrinkled nand thickened skin | ||
+ | ** Squamous cell carcinoma or haemangiosarcoma/haemangioma may develop | ||
+ | *Microscopically: | ||
+ | **Dyskeratotic cells | ||
+ | **Intercellular oedema | ||
+ | **Vacuolated keratinocytes | ||
+ | **Followed by [[Skin Glossary - Pathology|hyperkeratosis, parakeratosis and acanthosis]] | ||
+ | **Endothelial swelling | ||
+ | **Haemorrhage | ||
+ | **Hyperplasia | ||
+ | **Dermal fibrosis | ||
+ | **Dogs may develop actinic [[Skin Glossary - Pathology|comedones]] | ||
+ | |||
+ | [[Category:Integumentary System - Sunlight Damage]] | ||
+ | |||
+ | ===[[Photosensitisation]]=== | ||
+ | |||
+ | ===Photoenhanced dermatoses=== | ||
+ | *Many [[Skin Immunologic - Pathology|immune-mediated]] cutaneous disease are made worse by sunlight | ||
+ | **Lupus erythematosus | ||
+ | **Dermatomyositis | ||
+ | **Pemphigus erythematosus | ||
+ | *Vasculitis in extremities, especially white-haired horses | ||
+ | *Grossly: | ||
+ | **Erythematous, well circumscribed crusted lesions or hyperkeratotic [[Skin Glossary - Pathology|plaques]] | ||
+ | *Microscopically: | ||
+ | **Vasculitis of superficial dermal vessels | ||
+ | **Thrombi may be seen | ||
+ | |||
+ | [[Category:Integumentary System - Sunlight Damage]] |
Revision as of 16:04, 21 February 2011
Chemical damage
Contact Dermatitis
Ergot Poisoning
Fescue Poisoning
Selenium Poisoning
Physical damage
Acral Lick Dermatitis
Callus
Feline Psychogenic Alopecia
Injection site reaction
- May be caused by subcutaneous injections
- Granulomatous nodules form with central necrotic and foreign material
- Macrophages and multinucleated giant cells around the centre
- Surrounded by granulation tissue, perivascular lymphocytes that may form lymphoid follicles, eosinophils
- Cats may develop fibrosarcomas secondary to vaccination
- Dogs, especially poodles, may develop lymphoplasmacytic panniculitis and perivasculitis, vasculitis and follicular atrophy secondary to killed rabies vaccine
Intertrigo
- Also called skin fold dermatitis
- Develops due to irritation and bacteria in areas of skin friction and moisture (tears, saliva, glandular secretions, urine)
- Areas affected are commonly facial fold in brachycephalic breeds, lip fold, body fold, vulvular fold (obese females), tail fold (corkscrew tails)
- Cows with large, pendolous udder may become affected in area between thigh and udder
- In severe cases, skin and subcutis may slough
Pyotraumatic dermatitis
- Also called acute moist dermatitis or 'hot spot'
- Common in dogs, especially self-inflicted due to pain and itching
- Usual causes: allergies, irritants, matted hair, parasites
- Lesions tend to be worse in hot and humid weather
- Grossly:
- Hairless, red and moist lesion
- Fluid exudate
- Edges are circumscribed and red
- Microscopically:
- Superficial erosive to ulcerative exudative dermatitis
- May be deeper suppurative folliculitis
Radiation damage
- Cells sensitive to radiation include anagen hair follicles, germinal basal cells, melanocytes and endothelial cells
- Early changes:
- Erythema, epidermal blisters and oedema, erosions and ulceration
- Healed by scarring, hyperpigmentation with lower doses and hypopigmentation with higher doses
- Temporary or permanent alopecia
- Chronic changes:
- Scarring, altered pigmentation, alopecia
- Epidermal and adnexal atrophy
- Degeneration of vascular and elastic tissue
- Fibrosis of dermal and subcutaneous tissue
- Ulceration
- In severe damage, squamous cell carcinoma may develop
Low temperature damage
- Prolonged cold can cause ice crystal formation and vascular injury resultic in damage to tissue due to increased intracellular salt concentration
- Slow chilling can cause vasoconstriction, cellular damage -> secondary vasodilation and increased permeability -> oedema
- Severe and persistent cold causes vasoconstriction, increase in blood viscosity and tissue anoxia
- Lesions may occur in wet or hypoglycaemic neonates or animals recently moved from warm to cold environment
- Areas affected are extremities
- Lesions consist of gangrene and necrotic tissue
High temperature damage
- May result from excessive heat, liquids, flames, friction, lightning, electricity
- Partial or full thickness burns (first, second and third degree burns)
- Full thickness burns:
- Total destruction of skin and adnexa
- Has to be repaired by grafting
- Life threatening
- Partial thickness burns:
- Some structures preserved -> regeneration may occur
- Grossly:
- Erythema (capillary dilation)
- Oedema (increased permeability of capillaries)
- Vesicles
- Microscopically:
- Coagulation necrosis of epidermis
- Subepidermal vesiculation
- Necrosis of adnexa
- Degenerated subepidermal collagen
- May involve large numbers of neutrophils if secondary ifection is present
Sunlight damage
- Transient erythema may develop into sunburn erythema (warmth, swelling, pain)
- Diffusion of inflammatory mediators (e.g. cytokines) from damaged keratinocytes and endothelial cells
- Photooxidation of existing melanin -> pigment darkening
- Melanogenesis
- Immune responses of skin are reduced by UV light
Solar dermatosis and neoplasia
- Caused by chronic sunlight damage
- Damaged tissue generates free radicals than may damage nucleis acids and proteins
- If damage repaired prior to mitosis - no lasting effect
- If mitosis occurs before repair, post-mitotic repair is prone to faults and DNA mutations may result in neoplasia
Solar dermatitis
- Particularly in white animals and where little or no hair is present
- Grossly:
- Erythema, scaling and crusting
- -> Wrinkled nand thickened skin
- Squamous cell carcinoma or haemangiosarcoma/haemangioma may develop
- Microscopically:
- Dyskeratotic cells
- Intercellular oedema
- Vacuolated keratinocytes
- Followed by hyperkeratosis, parakeratosis and acanthosis
- Endothelial swelling
- Haemorrhage
- Hyperplasia
- Dermal fibrosis
- Dogs may develop actinic comedones
Photosensitisation
Photoenhanced dermatoses
- Many immune-mediated cutaneous disease are made worse by sunlight
- Lupus erythematosus
- Dermatomyositis
- Pemphigus erythematosus
- Vasculitis in extremities, especially white-haired horses
- Grossly:
- Erythematous, well circumscribed crusted lesions or hyperkeratotic plaques
- Microscopically:
- Vasculitis of superficial dermal vessels
- Thrombi may be seen