| IIM group (75 biopsies) | Aldolase+ group (12 biopsies) | p Value (IIM vs Ald+) | Jo-1 group (14 biopsies) | p Value (Jo-1 vs Ald+) | ||||
| No +ve | % +ve | No +ve | % +ve | No +ve | % +ve | |||
| Inflammation, cell foci | ||||||||
| Perimysial | 19 | 25 | 0 | 0 | 0.06 | 1 | 7 | 1.0 |
| Endomysial | 45 | 60 | 3 | 25 | 0.03 | 2 | 14 | 1.0 |
| Perivascular, med size vessel | 29 | 39 | 2 | 17 | 0.20 | 2 | 14 | 1.0 |
| Muscle fibre features | ||||||||
| Enlarged muscle fibres | 20 | 27 | 0 | 0 | 0.06 | 0 | 0 | 1.0 |
| Perifascicular | ||||||||
| Atrophy | 20 | 27 | 7 | 58 | 0.04 | 12 | 86 | 0.20 |
| Necrosis and regeneration | 10 | 13 | 4 | 33 | 0.09 | 7 | 50 | 0.45 |
| COX stain reduced | 7 | 9 | 2 | 17 | 0.60 | 1 | 7 | 1.0 |
| Regional necrosis | 4 | 5 | 0 | 0 | 1.0 | 0 | 0 | 1.0 |
| MHC I on muscle fibre surface | 64 | 85 | 10 | 83 | 1.0 | 13 | 93 | 0.58 |
| Perimysium | ||||||||
| Fragmentation | 17 | 23 | 9 | 75 | <0.001 | 13 | 93 | 0.31 |
| Alkaline phosphatase+ | 30 | 40 | 7 | 58 | 0.35 | 12 | 86 | 0.19 |
| AcP+ cells | 21 | 28 | 10 | 83 | <0.001 | 12 | 86 | 1.0 |
| Endomysium | ||||||||
| Increased connective tissue | 13 | 17 | 0 | 0 | 0.20 | 1 | 7 | 1.0 |
| C5b-9 deposition, diffuse | 15 | 20 | 0 | 0 | 0.12 | 2 | 7 | 0.48 |
| Capillaries | ||||||||
| Reduced number | 11 | 15 | 1 | 8 | 1.0 | 0 | 7 | 1.0 |
| Enlarged size | 14 | 19 | 0 | 0 | 0.20 | 1 | 7 | 1.0 |
| Alkaline phosphatase stain | 11 | 15 | 0 | 0 | 0.35 | 1 | 7 | 1.0 |
| C5b-9 deposition | 18 | 24 | 2 | 17 | 0.73 | 1 | 7 | 1.0 |
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Perimysial pathology, with fragmentation and acid phosphatase positive cellularity, were the only pathological features that differed from the IIM group.
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% +ve, per cent of biopsies positive; Ald+, patients with selectively elevated aldolase; alkaline phosphatase stain, increased number of endomysial capillaries with positive staining; IIM, immune or inflammatory myopathy group; inflammation, cell foci, foci of mononuclear inflammatory cells; No +ve, number of biopsies positive; Jo-1, patients with myopathies associated with serum anti-Jo-1 antibodies.
