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− | (MMM) | + | ==Overview== |
− | *Occurs in dogs
| + | 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
| + | *'''Acute stage''': Eosinophilic myositis with extremely swollen, painful, hard masticatory muscles. |
− | *Autoantibodies selectively attack muscles of mastication (type IIM fibres)
| + | *'''Chronic stage''': Atrophic myositis where atrophy may occur without previous acute stage. |
− | *Acute stage = eosinophilic myositis | + | |
− | **Extremely swollen, painful, hard masticatory muscles
| + | Grossly MMM is normally bilateral, but not necessarily symmetrical. |
− | *Chronic stage = atrophic myositis | + | |
− | **Atrophy may occur without previous acute stage
| + | ==Histology== |
− | *Grossly:
| + | |
− | **Bilateral but not necessarily symmetrical
| + | '''Acute lesions''': |
− | *Histologically:
| + | *Mainly eosinophilic infiltrate, few lymphocytes, [[Monocytes|monocytes]] and plasma cells. |
− | **Acute lesions:
| + | *In recurrent disease plasma cells predominate. |
− | ***Mainly eosinophilic infiltrate, few lymphocytes, [[Monocytes|monocytes]] and plasma cells
| + | *[[Muscle Necrosis|Necrotic]] myofibres, [[Muscle Atrophy|atrophy]] and attempted [[Muscle Regeneration|regeneration]]. |
− | ***In recurrent disease plasma cells predominate
| + | |
− | ***[[Muscle Necrosis|Necrotic]] myofibres, [[Muscle Atrophy|atrophy]] and attempted [[Muscle Regeneration|regeneration]]
| + | '''Chronic lesions''': |
− | **Chronic stage:
| + | *[[Muscle Atrophy|Atrophy]] predominates. |
− | ***[[Muscle Atrophy|Atrophy]] predominates
| + | *Fasciculi are shrunken. |
− | ***Fasciculi are shrunken
| + | *Condensation of stroma leading to an enlarged endomysium. |
− | ***Condensation of stroma -> enlarged endomysium
| + | *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.----------> | + | [[category:To Do - Mars Check]] |