![](../pics/biopsy/inflammation/bacm/bacmhelpar.jpg)
H&E stain
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Necrosis: Regional, Early stage
Large cluster of necrotic fibers (Arrows) with
Cytoplasm: Dark or Very Pale
Internal architecture & Myonuclei: Lost
Perimysium near region of clustered necrosis
Fragmented & Pale connective tissue
Wide
![](../pics/biopsy/inflammation/bacm/bacmvvglpar.jpg)
VvG stain
|
Necrosis: Regional, Early stage
Large cluster of necrotic fibers (Arrow) with
Cytoplasm: Dark or Very Pale
Internal architecture & Myonuclei: Lost
Perimysium near region of clustered necrosis
Fragmented & Pale connective tissue
Wide
![](../pics/biopsy/inflammation/bacm/bacmgtlpar.jpg)
Gomori trichrome stain
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Necrosis: Regional, Early stage
Large region containing very pale necrotic fibers (Arrows)
![](../pics/biopsy/inflammation/bacm/bacmnadhlpar.jpg)
NADH stain
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Necrosis: Regional, Early stage
Scattered fibers in region of necrosis have intermediate staining
Perimysial vein (Arrow): Pale staining wall
![](../pics/biopsy/inflammation/bacm/bacmatp43lpar.jpg)
ATPase pH 4.3 stain
|
Necrosis: Regional, Early stage
Histiocytes (Acid phosphatase +): Scattered in perimysium & endomysium
In this early stage, and likely due to an ischemic nature of the process, there is no invasion of muscle fibers by histiocytes
![](../pics/biopsy/inflammation/bacm/bacmacplp.jpg)
Acid phosphatase stain
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Necrosis: Regional, Early stage
Perimysium: Only minor staining
Muscle fibers: No staining around fibers in region of necrosis
![](../pics/biopsy/inflammation/bacm/bacmalplp.jpg)
Alkaline phosphatase stain
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Necrosis: Regional, Early stage
![](../pics/biopsy/inflammation/bacm/bacmcoxlp.jpg)
COX stain
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Mitochondrial stains: Many muscle fibers in region of necrosis stain pale for SDH and COX
![](../pics/biopsy/inflammation/bacm/bacmsdhlp.jpg)
SDH stain
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Necrosis: Regional, Early stage
Muscle fibers outside region of necrosis have increased MHC1 on their surfaces
![](../pics/biopsy/inflammation/bacm/bacmmhc1.jpg)
MHC I stain
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![](../pics/biopsy/inflammation/bacm/bacmc5b9lp.jpg)
C5b-9 stain
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Necrosis: Regional, Early stage
C5b-9
Region of clustered necrosis (Above): Stains cytoplasm of many muscle fibers
Necrotic muscle fibers
Are mostly located near avascular perimysium
Endomysial capillaries: Many stained for C
5b-9
Perimysial connective tissue: Diffusely stained for C
5b-9
Region with only scattered muscle fiber necrosis (Below)
C
5b-9 stains many endomysial capillaries
Perimysial connective tissue: Some areas stained for C
5b-9
![](../pics/biopsy/inflammation/bacm/bacmc5b9b.jpg)
C5b-9 stain
|
![](../pics/biopsy/inflammation/bacm/bacmvessgtmp.jpg)
Gomori trichrome stain
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Perimysial Vessels
Surrounded by damaged perimysium populated by increased cellularity (probably histiocytes).
![](../pics/biopsy/inflammation/bacm/bacmvesshe.jpg)
H&E stain
|
![](../pics/biopsy/inflammation/bacm/bacmvessvvg.jpg)
VvG stain
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Perimysial Vessels
Vessel walls are abnormal with loss of fibrils.
![](../pics/biopsy/inflammation/bacm/bacmvessvvg2.jpg)
VvG stain
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![](../pics/biopsy/inflammation/bacm/bacmdarkneche.jpg)
H&E stain
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Necrotic muscle fibers
Early necrotic fibers: Have
"Dark" necrosis with dark stained featureless cytoplasm and no myonuclei
Some non-necrotic fibers (Bottom Right) have retained sarcoplasmic reticulum staining in cytoplasm
Later necrotic fibers: Pale, fragmented cytoplasm with no associated histiocytes
![](../pics/biopsy/inflammation/bacm/bacmdarknec.jpg)
Gomori trichrome stain
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Necrosis, Later stage
Many
Pale-stained fibers (Arrow) with: Fragmented cytoplasm; No associated histiocytes
Scattered
"Dark" Necrotic Fibers are also present
![](../pics/biopsy/inflammation/bacm/bacmdarkneclategtar.jpg)
Gomori trichrome stain
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11/10/2022