Wedderburn et al reported a scoring system for evaluating muscle biopsies from a patient with juvenile dermatomyositis. This consists of 4 domains and a visual analogus scale (VAS).
Patient selection: juvenile dermatomyositis
Parameters for the muscle fiber domain, quantitative:
(1) perifascicular atrophy
(2) neonatal myosin
(3) regeneration/degeneration/fibrosis peri-fascicular
(4) regeneration/degeneration/fibrosis non-perifascicular
(5) internal myonuclei in non-basophilic, otherwise normal, fibers
|
Parameter
|
Finding
|
Points
|
|
perifascicular atrophy
|
none
|
0
|
|
|
1 or 2 fascicles
|
1
|
|
|
>= 3 fascicles
|
2
|
|
neonatal myosin
|
< 6 positive fibers in 20x objective field
|
0
|
|
|
>= 6 positive fibers in 20 x objective field
|
1
|
|
peri-fascicular changes
|
none
|
0
|
|
|
1 or 2 fasciculi
|
1
|
|
|
>= 3 fasciculi
|
2
|
|
non-perifascicular changes
|
none
|
0
|
|
|
1 or 2 fasciculi
|
1
|
|
|
>= 3 fasciculi
|
2
|
|
internal myonuclei
|
< 3% of fibers
|
0
|
|
|
>= 3% of fibers
|
1
|
subscore for muscle fiber domain items 1 to 5=
= SUM(points for all of the parameters)
Parameters for the muscle fiber domain, qualitative:
(1) over-expression of stain for MHC Class I
(2) non-perifascicular fiber atrophy
subscore for qualitative muscle fiber parameters =
= (number of items present)
Parameters of the connective tissue domain:
(1) any endomysial fibrosis
(2) any perimysial fibrosis
subscore for connective tissue domain =
= (number of items present)
Parameter for the global domain:
(1) VAS scale from 0 (normal) to 10 (extensive abnormalities)
Interpretation:
• minimum subscores: 0
• maximum quantitative muscle fiber domain subscore: 8
• maximum number of qualitative muscle fiber domain items: 2
• maximum number of connective tissue domain items: 2
