Difference between revisions of "Muscles Inflammatory - Pathology"

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#redirect[[:Category:Muscles - Inflammatory Pathology]]
 
 
{{toplink
 
|backcolour =CDE472
 
|linkpage =Musculoskeletal System - Pathology
 
|linktext =Musculoskeletal System
 
|maplink = Musculoskeletal System (Content Map) - Pathology
 
|pagetype =Pathology
 
|sublink1=Muscles - Pathology
 
|subtext1=MUSCLES
 
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<br>
 
==Myositis==
 
 
 
*Inflammation of muscle
 
 
 
 
 
===Bacterial myositis===
 
 
 
*Bacteria gain entry via:
 
**Direct penetration
 
**Blood stream
 
**Extension
 
*Lesions caused:
 
**Suppurative
 
**Serosanguinous
 
**Granulomatous
 
 
 
 
 
====Abscesses====
 
 
 
*Caused by pyogenic bacteria
 
*Usually:
 
**[[Arcanobacter pyogenes|''Arcanobacterium pyogenes'']] in sheep and cattle
 
**[[Respiratory Bacterial Infections - Pathology#Strangles|''Streptococcus equi'']] in horses
 
**''[[Corynebacterium pseudotuberculosis]]'' in sheep and goats
 
**[[Pasteurella multocida|''Pasteurella multocida'']] causes cellulitis in cats
 
*Usually localised suppuration and necrosis of myofibres
 
*Occasionally my spread via the fascia
 
 
 
 
 
====[[Black Leg]]====
 
 
 
====[[Gas Gangrene|Gas gangrene]]====
 
 
 
====[[Actinobacillosis|Wooden tongue]]====
 
 
 
====[[Tuberculosis]]====
 
 
 
====''[[Actinomyces bovis]]''====
 
*"[[Lumpy jaw]]"
 
 
 
====[[Botryomycosis]]====
 
 
 
 
 
 
 
 
 
===Viral myositis===
 
 
 
*Rare in the UK
 
 
 
====[[Porcine encephalomyelitis]]====
 
 
 
====[[Foot and Mouth Disease]]====
 
 
 
 
 
====[[Bluetongue Virus|Bluetongue]]====
 
 
 
===Parasitic myositis===
 
 
 
[[Image:Sarcocyst in muscle.jpg|right|thumb|100px|<small><center>Sarcocyst (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 
*Rare in domestic animals
 
 
 
 
 
====Nematodes====
 
 
 
*[[Trichinella|'''''Trichinella''''']] larvae
 
 
 
 
 
*[[Ancylostomatoidea|''Ancylostoma'']] larvae
 
**Cause inflammation and [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
 
*[[Ascaridoidea|Ascarid]] larvae
 
*[[Dirofilaria immitis|''Dirofilaria immitis'']] in dogs causing ischaemic myopathy due to [[Muscles Degenerative - Pathology#Ischaemia|infartcs]]
 
 
 
====Cestodes====
 
 
 
*[[Taenia|''Taenia solium, '']] - cysticercosis in swine and humans
 
*[[Taenia|''T. ovis'']] - cysticercosis in sheep
 
*[[Taenia|''T. saginata'']] in cattle cysticercosis
 
*[[Taenia|''Multiceps serialis'']] in rabbits, primates coenurosis
 
*[[Echinococcus|''Echinococcus granulosus'']] hydatid disease in herbivores and humans
 
 
 
====Protozoa====
 
 
 
*[[Toxoplasma|'''''Toxoplasma gondii''''']]
 
 
 
*[[Neospora|'''''Neospora caninum''''']]
 
 
 
*[[Sarcocystis|'''''Sarcocystis''''']]
 
**Histologically:
 
***Merozoites causing focal and segmental [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
 
***May involve [[Muscles Degenerative - Pathology#Calcification|mineralisation]]
 
***Non-purulent myositis with plasma cells, lymphocytes and macrophages
 
**Diaphragm and masseters most severely affected
 
*[[Bones Hyperplastic and Neoplastic - Pathology#Hepatozoon|'''''Hepatozoon americanum''''']]
 
**Develop cysts in skeletal muscle of dogs and cats
 
**May be accompanied by pyogranulomatous myositis - macrophages and [[Neutrophils|neutrophils]] mainly with occasional other cells
 
*'''''Trypanosoma'''''
 
**Infrequent muscle lesions with mononuclear infiltrates
 
**Dogs, cats and pigs are affected
 
**Parasites lie between myofilaments
 
**May cause fibre degeneration
 
*'''''Babesia bovis'''''
 
**In cattle
 
**Infrequent muscle [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
 
 
 
====Arthropods====
 
 
 
*Dipterious larvae causing myiasis
 
*[[Insecta|''Hypoderma'' spp.]] in cattle
 
**May occasionally burrow into muscle
 
 
 
===Immune-mediated myositis===
 
 
 
====Masticatory muscle myositis (MMM)====
 
 
 
*Occurs in dogs
 
*Tends to affect the masseter and temporalis muscles
 
*Autoantibodies selectively attack muscles of mastication (type IIM fibres)
 
*Acute stage = eosinophilic myositis
 
**Extremely swollen, painful, hard masticatory muscles
 
*Chronic stage = atrophic myositis
 
**Atrophy may occur without previous acute stage
 
*Grossly:
 
**Bilateral but not necessarily symmetrical
 
**At first, enlarged and oedematous muscles becominf dark red, firm with reddish streaks and yellowiss foci
 
*Histologically:
 
**Acute lesions:
 
***Mainly eosinophilic infiltrate, few lymphocytes, [[Monocytes|monocytes]] and plasma cells
 
***In recurrent disease plasma cells predominate
 
***[[Muscles Degenerative - Pathology#Necrosis|Necrotic]] myofibres, [[Muscles Degenerative - Pathology#Atrophy|atrophy]] and attempted [[Muscle Regeneration - Anatomy & Physiology|regeneration]]
 
**Chronic stage:
 
***[[Muscles Degenerative - Pathology#Atrophy|Atrophy]] predominates
 
***Fasciculi are shrunken
 
***Condensation of stroma -> enlarged endomysium
 
***Focal plasma cell and lymphocyte infiltration
 
 
 
====[[Muscles Developmental - Pathology#Canine dermatomyositis|Canine dermatomyositis]]====
 
 
 
 
 
===Idiopathic myositis===
 
 
 
====Canine polymyositis====
 
 
 
*DOES NOT include MMM above
 
*Rare
 
*Clinical signs:
 
**Muscle pain
 
**Fever
 
**Weakness, particularly in hind limbs
 
*Grossly:
 
**Inflammation is accompanied by muscle necrosis and regeneration
 
*Histologically:
 
**Inflammatory foci with lymphocytes, plasma cells and occasionally eosinophils
 
*Possibly immunological cause
 
*Single biopsy may not be enough to make the diagnosis as it tends to be multifocal and disseminated
 
*Lesions similar to some infectious causes (such as [[Toxoplasma|''Toxoplasma gondii'']])
 
 
 
====Canine bilateral extraocular polymyositis====
 
 
 
*In Golden retrievers
 
*Very rare
 
*Clinical signs:
 
**Acute bilateral exophthalmos
 
*Involves only extraocular muscles except for retractor blbi
 
*Grossly:
 
**Swollen and pale extraocular muscles
 
*Histologically:
 
**Sterile myositis
 
**Multifocal necrosis of myofibres
 
**Lymphocytic, histiocytic and plasmacytic infiltrate with few [[Neutrophils|neutrophils]]
 
 
 
 
 
====Bovine and ovine eosinophilic myositis====
 
 
 
*Unknown aetiology
 
*Major cell involved is eosinphil
 
*Usually noticed at slaughter - green muscle discoloration
 
*May be caused by degenteration of [[Sarcocystis|''Sarcocystis'' spp.]]
 
*Grossly:
 
**Green discolored areas, well demarcated
 
**Mostly in muscles of back and thighs
 
*Histologically:
 
**Massive eosinophil infiltration
 
**Muscle fibres may degenerate
 
**In old lesions - endimysial fibrosis, myofibre atrophy, some regeneration, lymphocytes, plasma cells, macrophages and few eosinophils
 
**Capsule may form
 

Latest revision as of 23:15, 5 March 2011