Difference between revisions of "Muscles Inflammatory - Pathology"

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#redirect[[:Category:Muscles - Inflammatory Pathology]]
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{{review}}
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{{toplink
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|backcolour =CDE472
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|linkpage =Musculoskeletal System - Pathology
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|linktext =Musculoskeletal System
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|maplink = Musculoskeletal System (Content Map) - Pathology
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|pagetype =Pathology
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|sublink1=Muscles - Pathology
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|subtext1=MUSCLES
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}}
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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===
 +
 
 +
 
 +
*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''''']]
 +
 
 +
*[[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

Revision as of 10:49, 1 July 2010

 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.


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()Map MUSCULOSKELETAL SYSTEM (Map)
MUSCLES



Myositis

  • Inflammation of muscle


Bacterial myositis

  • Bacteria gain entry via:
    • Direct penetration
    • Blood stream
    • Extension
  • Lesions caused:
    • Suppurative
    • Serosanguinous
    • Granulomatous


Abscesses


Black Leg

Gas gangrene

Wooden tongue

Tuberculosis

Actinomyces bovis

Botryomycosis

Viral myositis

  • Rare in the UK

Porcine encephalomyelitis

Foot and Mouth Disease

Bluetongue

Parasitic myositis

  • Rare in domestic animals


Nematodes


Cestodes

Protozoa

  • Hepatozoon americanum
    • Develop cysts in skeletal muscle of dogs and cats
    • May be accompanied by pyogranulomatous myositis - macrophages and 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

Arthropods

  • Dipterious larvae causing myiasis
  • 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:
    • Chronic stage:
      • Atrophy predominates
      • Fasciculi are shrunken
      • Condensation of stroma -> enlarged endomysium
      • Focal plasma cell and lymphocyte infiltration

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 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


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 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
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