Histopathology Methods for Strep Cell Wall Reactivation Arthritis

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Processing of Knee Joints

Knees are cut in half in the frontal plane and the two halves are embedded together in a paraffin block. Sections are cut from each block and stained with toluidine blue (t. blue).

Evaluation of Joints

The following parameters are scored according to the indicated criteria:

Inflammation Score

• 0 = Normal
• 0.5 = Minimal, generally focal infiltration of inflammatory cells in synovium
• 1 = Minimal diffuse infiltration of inflammatory cells in synovium
• 2 = Mild diffuse infiltration of inflammatory cells in synovium and extending into periarticular tissues
• 3 = Moderate diffuse infiltration with moderate edema in synovium and extending into periarticular tissues
• 4 = Marked diffuse infiltration with marked edema in synovium and extending into periarticular tissues
• 5 = Severe diffuse infiltration with severe edema in synovium and extending into periarticular tissues

Pannus Score

• 0 = Normal
• 0.5 = Very minimal, focal or only a few marginal zones affected
• 1 = Minimal infiltration of pannus in cartilage and subchondral bone, primarily affects marginal zones
• 2 = Mild infiltration (<1/4 of tibia at marginal zones)
• 3 = Moderate infiltration (1/4 to 1/3 of tibia affected at marginal zones)
• 4 = Marked infiltration (1/2 to 3/4 of tibia affected at marginal zones)
• 5 = Severe infiltration (>3/4 of tibia affected at marginal zones, severe distortion of overall architecture)

Cartilage Damage Score

• 0 = Normal
• 0.5 = Very minimal: Focal or only a few marginal zones affected
• 1 = Minimal: Minimal to mild loss of toluidine blue staining with no obvious chondrocyte loss or collagen disruption, lesions mainly in marginal zones
• 2 = Mild: Mild loss of t. blue staining with focal mild (superficial) chondrocyte loss and/or collagen disruption mainly in marginal zones, may have one to two small areas of more severe degeneration
• 3 = Moderate: Moderate loss of toluidine blue staining with multifocal moderate (depth to middle zone) chondrocyte loss and/or collagen disruption on at least one surface but still mainly in marginal zones, may have one to two small areas of more severe degeneration
• 4 = Marked: Marked loss of toluidine blue staining with multifocal marked (depth to deep zone or tidemark) chondrocyte loss and/or collagen disruption on at least one surface
• 5 = Severe: Severe diffuse loss of toluidine blue staining with multifocal severe (depth to tidemark) chondrocyte loss and/or collagen disruption affecting more than two cartilage surfaces

Bone Resorption Score

• 0 = Normal
• 0.5 = Very minimal: Normal on low magnification but with the earliest hint of small focal areas of resorption in a marginal zone
• 1 = Minimal: Small definite areas of resorption in marginal zones only
• 2 = Mild: Small areas of resorption in marginal zones and extending up to ¼ of the distance across the affected surface
• 3 = Moderate: Areas of resorption extend beyond marginal zones >1/4 but less than 1/2 of the subchondral surface
• 4 = Marked: Areas of resorption extend beyond marginal zones >1/2 but less than 3/4 of the subchondral surface
• 5 = Severe: Areas of resorption extend beyond marginal zones >3/4 of the subchondral surface

Summed Score

A sum of the four histopathology scores is also calculated for each joint.

Processing of Ankle Joints

Ankles are cut in half longitudinally and the two halves are embedded together in a paraffin block. Sections are cut from each block and stained with toluidine blue (t. blue).

Evaluation of Joints

The following parameters are scored according to the indicated criteria:

Inflammation Score

• 0 = Normal
• 0.5 = Very minimal, generally focal infiltration of inflammatory cells in synovium
• 1 = Minimal diffuse or mild focal infiltration of inflammatory cells in synovium
• 2 = Mild diffuse infiltration of inflammatory cells in synovium and extending into periarticular tissues
• 3 = Moderate diffuse infiltration with moderate edema in synovium and extending into periarticular tissues
• 4 = Marked diffuse infiltration with marked edema in synovium and extending into periarticular tissues
• 5 = Severe diffuse infiltration with severe edema in synovium and extending into periarticular tissues

Pannus Score

• 0 = Normal
• 0.5 = Very minimal, focal or only a few marginal zones affected
• 1 = Minimal infiltration of pannus in cartilage and subchondral bone, primarily affects marginal zones
• 2 = Mild infiltration (<1/4 of tibia or tarsals at marginal zones)
• 3 = Moderate infiltration (1/4 to 1/3 of tibia or small tarsals affected at marginal zones)
• 4 = Marked infiltration (1/2 to 3/4 of tibia or tarsals affected at marginal zones)
• 5 = Severe infiltration (>3/4 of tibia or tarsals affected at marginal zones, severe distortion of overall architecture)

Cartilage Damage Score

• 0 = Normal
• 0.5 = Very minimal: Focal or only a few marginal zones affected mainly with loss of toluidine blue staining
• 1 = Minimal: Minimal to mild loss of t. blue staining with minor chondrocyte loss or collagen disruption, lesions mainly in marginal zones, may have at least one affected cartilage surface with more severe changes
• 2 = Mild: Mild loss of t. blue staining with focal mild chondrocyte loss and/or collagen disruption mainly in marginal zones, may have one to two small areas of more severe degeneration on cartilage surfaces
• 3 = Moderate: Moderate loss of t.blue staining with multifocal moderate (depth to middle zone) chondrocyte loss and/or collagen disruption on at least ones surface, may have one to two small areas/cartilage surfaces with more severe degeneration, most marginal zones affected
• 4 = Marked: Marked loss of t. blue staining with multifocal marked (depth to deep zone or tidemark) chondrocyte loss and/or collagen disruption on at least one surface, all marginal zones affected
• 5 = Severe: Severe diffuse loss of t. blue staining with multifocal severe (depth to tidemark) chondrocyte loss and/or collagen disruption affecting more than one cartilage surface, all marginal zones affected

Bone Resorption Score

• 0 = Normal
• 0.5 = Very minimal: Small focal areas of resorption in a marginal zone or affecting bone below one cartilage surface
• 1 = Minimal: Small definite areas of resorption in several marginal zones and/or a single cartilage surface
• 2 = Mild: Small areas of resorption in marginal zones and extending up to ¼ of the distance across the affected surface, may have at least one affected cartilage surface as well
• 3 = Moderate: Areas of resorption extend beyond marginal zones >1/4 but less than 1/2 of the subchondral surface, may have at least one or more affected cartilage surfaces as well
• 4 = Marked: Areas of resorption extend beyond marginal zones >1/2 but less than 3/4 of the subchondral surface, may have at least one or more affected cartilage surface as well
• 5 = Severe: Areas of resorption extend beyond marginal zones >3/4 of the subchondral surface, may have at least one or more affected cartilage surface as well

Summed Score

A sum of the four histopathology scores is also calculated for each joint.

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Related Pages:

• Collagen Induced Arthritis (CIA) in Rat
• Collagen Induced Arthritis in Mice (Mouse CIA)
• Antibody Induced Arthritis in Mouse (ManIA)
• Strep Cell Wall (SCW) Reactivation Arthritis (PGPS)
• Adjuvant Arthritis (AIA) in Rat
• Antigen Induced Knee Arthritis (Mouse)

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