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(MMM)
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==Overview==
*Occurs in dogs
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Masticatory muscle myositis (MMM) occurs in dogs and tends to affect the [[Mastication#Jaw Closing Muscles|masseter]] and [[Cheeks|temporalis]] muscles. Autoantibodies selectively attack the muscle of mastication, which contain type IIM fibres. MMM can be classified as either acute or chronic:
*Tends to affect the masseter and temporalis muscles
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*'''Acute stage''': Eosinophilic myositis with extremely swollen, painful, hard masticatory muscles.
*Autoantibodies selectively attack muscles of mastication (type IIM fibres)
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*'''Chronic stage''': Atrophic myositis where atrophy may occur without previous acute stage.
*Acute stage = eosinophilic myositis
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**Extremely swollen, painful, hard masticatory muscles
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Grossly MMM is normally bilateral, but not necessarily symmetrical.
*Chronic stage = atrophic myositis
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**Atrophy may occur without previous acute stage
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==Histology==
*Grossly:
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**Bilateral but not necessarily symmetrical
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'''Acute lesions''':  
*Histologically:
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*Mainly eosinophilic infiltrate, few lymphocytes, [[Monocytes|monocytes]] and plasma cells.
**Acute lesions:
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*In recurrent disease plasma cells predominate.
***Mainly eosinophilic infiltrate, few lymphocytes, [[Monocytes|monocytes]] and plasma cells
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*[[Muscle Necrosis|Necrotic]] myofibres, [[Muscle Atrophy|atrophy]] and attempted [[Muscle Regeneration|regeneration]].
***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 lesions''':
**Chronic stage:
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*[[Muscle Atrophy|Atrophy]] predominates.
***[[Muscle Atrophy|Atrophy]] predominates
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*Fasciculi are shrunken.
***Fasciculi are shrunken
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*Condensation of stroma leading to an enlarged endomysium.
***Condensation of stroma -> enlarged endomysium
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*Focal plasma cell and lymphocyte infiltration.
***Focal plasma cell and lymphocyte infiltration
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[[Category:Other Oral Conditions]]
 
[[Category:Other Oral Conditions]]
 
[[Category:LisaM reviewing]]
 
[[Category:LisaM reviewing]]
[[category:To Do - Dentistry preMars]] <!-----G, please make it look nicer, ta.---------->
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[[category:To Do - Mars Check]]

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