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− | ==Myositis==
| + | #redirect[[:Category:Muscles - Inflammatory Pathology]] |
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− | [[Bacterial Myositis]] | |
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− | ===[[Viral Myositis]]===
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− | ===[[Parasitic Myositis]]===
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− | ===[[Immune-Mediated myositis]]===
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− | ====Masticatory muscle myositis (MMM)====
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− | *Occurs in dogs
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− | *Tends to affect the masseter and temporalis muscles
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− | *Autoantibodies selectively attack muscles of mastication (type IIM fibres)
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− | *Acute stage = eosinophilic myositis
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− | **Extremely swollen, painful, hard masticatory muscles
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− | *Chronic stage = atrophic myositis
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− | **Atrophy may occur without previous acute stage
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− | *Grossly:
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− | **Bilateral but not necessarily symmetrical
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− | **At first, enlarged and oedematous muscles becominf dark red, firm with reddish streaks and yellowiss foci
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− | *Histologically:
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− | **Acute lesions:
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− | ***Mainly eosinophilic infiltrate, few lymphocytes, [[Monocytes|monocytes]] and plasma cells
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− | ***In recurrent disease plasma cells predominate
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− | ***[[Muscle Necrosis|Necrotic]] myofibres, [[Muscle Atrophy|atrophy]] and attempted [[Muscle Regeneration|regeneration]]
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− | **Chronic stage:
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− | ***[[Muscle Atrophy|Atrophy]] predominates
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− | ***Fasciculi are shrunken
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− | ***Condensation of stroma -> enlarged endomysium
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− | ***Focal plasma cell and lymphocyte infiltration
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− | [[Category:Muscles - Inflammatory Pathology]]
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− | ====[[Canine Dermatomyositis|Canine dermatomyositis]]====
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− | ===Idiopathic myositis===
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− | ====Canine polymyositis====
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− | *DOES NOT include MMM above
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− | *Rare
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− | *Clinical signs:
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− | **Muscle pain
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− | **Fever
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− | **Weakness, particularly in hind limbs
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− | *Grossly:
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− | **Inflammation is accompanied by muscle necrosis and regeneration
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− | *Histologically:
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− | **Inflammatory foci with lymphocytes, plasma cells and occasionally eosinophils
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− | *Possibly immunological cause
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− | *Single biopsy may not be enough to make the diagnosis as it tends to be multifocal and disseminated
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− | *Lesions similar to some infectious causes (such as ''[[Toxoplasma gondii]]'')
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− | [[Category:Muscles - Inflammatory Pathology]]
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− | ====Canine bilateral extraocular polymyositis====
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− | *In Golden retrievers
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− | *Very rare
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− | *Clinical signs:
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− | **Acute bilateral exophthalmos
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− | *Involves only extraocular muscles except for retractor blbi
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− | *Grossly:
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− | **Swollen and pale extraocular muscles
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− | *Histologically:
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− | **Sterile myositis
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− | **Multifocal necrosis of myofibres
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− | **Lymphocytic, histiocytic and plasmacytic infiltrate with few [[Neutrophils|neutrophils]]
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− | [[Category:Muscles - Inflammatory Pathology]]
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− | ====Bovine and ovine eosinophilic myositis====
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− | *Unknown aetiology
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− | *Major cell involved is eosinphil
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− | *Usually noticed at slaughter - green muscle discoloration
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− | *May be caused by degenteration of [[Sarcocystis|''Sarcocystis'' spp.]]
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− | *Grossly:
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− | **Green discolored areas, well demarcated
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− | **Mostly in muscles of back and thighs
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− | *Histologically:
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− | **Massive eosinophil infiltration
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− | **Muscle fibres may degenerate
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− | **In old lesions - endimysial fibrosis, myofibre atrophy, some regeneration, lymphocytes, plasma cells, macrophages and few eosinophils
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− | **Capsule may form
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− | [[Category:Muscles - Inflammatory Pathology]]
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− | [[Category:Musculoskeletal System - Pathology]]
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