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====
 +
 
 +
*Caused by ''[[Mycobacterium bovis]]''
 +
*Grossly:
 +
**Yellowish spherical nodules
 +
**[[Necrosis - Pathology#Caseation Necrosis|Caseous content]]
 +
**Fibrous capsule usually
 +
*Histologically:
 +
**Granuloma
 +
**Central necrosis
 +
**Epitheliod and giant cells at periphery
 +
 
 +
 
 +
====''[[Actinomyces bovis]]''====
 +
*"Lumpy jaw"
 +
*May extend to muscles, especially masseters, from [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]]
 +
*Histologically:
 +
**Caseous or suppurative centres of lesions
 +
**Epithelioid and giant cells at periphery
 +
**'Sulfa granules' at centre - gram-positive branching rods
 +
 
 +
====[[Botryomycosis]]====
 +
 
 +
 
 +
 
 +
 
 +
===Viral myositis===
 +
 
 +
*Rare in the UK
 +
 
 +
====[[Porcine encephalomyelitis]]====
 +
 
 +
====Foot and Mouth disease====
 +
 
 +
*Caused by [[Picornaviridae|Apthovirus]]
 +
*Main presentation are vesicles
 +
*May also involve skeletal and heart muscle
 +
*Grossly:
 +
**Yellow streaks and grey foci
 +
*Histologically:
 +
**Segmental myofibre [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
 +
**Infiltration of lymphocytes and [[Neutrophils|neutrophils]]
 +
 
 +
 
 +
====[[Bluetongue Virus|Bluetongue]]====
 +
 
 +
*Caused by [[Reoviridae|bluetongue virus of family Reoviridae]]
 +
*Non-contagious
 +
*Insect-borne
 +
*Causes vasculitis, especially in oral cavity
 +
*Grossly:
 +
**Infarctions -> necrosis
 +
**Haemorrhage
 +
*Histologically:
 +
**Necrosis -> calcification or regeneration (depends on age of lesion)
 +
 
 +
 
 +
===Parasitic myositis===
 +
[[Image:taenia ovis cysticerci.jpg|right|thumb|100px|<small><center>''T. ovis'' cysticerci (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 +
[[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====
 +
 
 +
*[[Trichinelloidea|'''''Trichinella''''']] larvae
 +
**Particularly in pigs and dogs
 +
**Public health and economic importance
 +
**''T. spiralis'' affecting dogs, pigs, cats and humans is most common in hotter climates
 +
**Larvae distend myofibres
 +
**May be seen grossly if dead and calcified
 +
**Predilection for active muscles, ''e.g.'' diaphragm, intercostal, masseter and tongue muscles
 +
**Histologically:
 +
***Focal myositis - [[Neutrophils|neutrophils]], lymphocytes, eosinophils
 +
 
 +
*[[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''''']]
 +
**Cats as final hosts
 +
**Intermediate hosts, birds and mammals have tachyzoites throughout body, infrequently in skeletal muscle
 +
**Histologically:
 +
***Multifocal [[Muscles Degenerative - Pathology#Necrosis|necrosis]] of myofibres
 +
***Lymphocyte and plasma cell infiltration
 +
***In later stages bradyzoite cysts
 +
*[[Neospora|'''''Neospora caninum''''']]
 +
**Necrotising inflammation of muscles
 +
**Myositis more severe than in toxoplasmosis
 +
*[[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

Revision as of 10:38, 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

  • Caused by Mycobacterium bovis
  • Grossly:
  • Histologically:
    • Granuloma
    • Central necrosis
    • Epitheliod and giant cells at periphery


Actinomyces bovis

  • "Lumpy jaw"
  • May extend to muscles, especially masseters, from osteomyelitis
  • Histologically:
    • Caseous or suppurative centres of lesions
    • Epithelioid and giant cells at periphery
    • 'Sulfa granules' at centre - gram-positive branching rods

Botryomycosis

Viral myositis

  • Rare in the UK

Porcine encephalomyelitis

Foot and Mouth disease

  • Caused by Apthovirus
  • Main presentation are vesicles
  • May also involve skeletal and heart muscle
  • Grossly:
    • Yellow streaks and grey foci
  • Histologically:


Bluetongue

  • Caused by bluetongue virus of family Reoviridae
  • Non-contagious
  • Insect-borne
  • Causes vasculitis, especially in oral cavity
  • Grossly:
    • Infarctions -> necrosis
    • Haemorrhage
  • Histologically:
    • Necrosis -> calcification or regeneration (depends on age of lesion)


Parasitic myositis

T. ovis cysticerci (Image sourced from Bristol Biomed Image Archive with permission)
Sarcocyst (Image sourced from Bristol Biomed Image Archive with permission)
  • Rare in domestic animals


Nematodes

  • Trichinella larvae
    • Particularly in pigs and dogs
    • Public health and economic importance
    • T. spiralis affecting dogs, pigs, cats and humans is most common in hotter climates
    • Larvae distend myofibres
    • May be seen grossly if dead and calcified
    • Predilection for active muscles, e.g. diaphragm, intercostal, masseter and tongue muscles
    • Histologically:


Cestodes

Protozoa

  • Toxoplasma gondii
    • Cats as final hosts
    • Intermediate hosts, birds and mammals have tachyzoites throughout body, infrequently in skeletal muscle
    • Histologically:
      • Multifocal necrosis of myofibres
      • Lymphocyte and plasma cell infiltration
      • In later stages bradyzoite cysts
  • Neospora caninum
    • Necrotising inflammation of muscles
    • Myositis more severe than in toxoplasmosis
  • Sarcocystis
    • Histologically:
      • Merozoites causing focal and segmental necrosis
      • May involve mineralisation
      • Non-purulent myositis with plasma cells, lymphocytes and macrophages
    • Diaphragm and masseters most severely affected
  • 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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