Muscle biopsy features, treatments, and duration of disease at biopsy according to autoantibody subsets in patients with dermatomyositis (DM).
| All DM, n = 91 | All Jo1, n = 13; 14% | Jo1 with Ro52, n = 9; 10% | Jo1 without Ro52, n = 4; 4% | Anti–TIF1-γ, n = 25; 27% | NXP2, n = 17; 19% | Mi-2, n = 12; 13% | MDA5, n = 5; 5% | PM-Scl, n = 9; 10% | Ro52, n = 22; 24% | No Antibody, n = 15; 16% | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Perivascular inflammation | 56 (62%) | 9 (69%) | 8 (89%) | 1 (25%) | 16 (64%) | 11 (65%) | 10 (83%) | 1 (20%) | 7 (78%) | 15 (68%) | 6 (40%) |
| Perifascicular atrophy | 46 (51%) | 8 (62%) | 7 (78%) | 1 (25%) | 16 (64%) | 9 (53%) | 8 (67%) | 2 (40%) | 3 (33%) | 12 (55%) | 4 (27%) |
| Primary inflammation | 21 (23%) | 4 (31%) | 4 (44%) | 0 (0%) | 3 (12%) | 0 (0%) | 6 (50%) | 0 (0%) | 6 (67%) | 6 (27%) | 3 (20%) |
| Mitochondrial dysfunction* | 14 (28%) | 2 (25%) | 2 (29%) | 0 (0%) | 7 (47%) | 2 (25%) | 2 (29%) | 1 (50%) | 0 (0%) | 4 (29%) | 1 (14%) |
| Necrotizing myopathy | 15 (16%) | 2 (15%) | 0 (0%) | 2 (50%) | 2 (8%) | 3 (18%) | 1 (8%) | 0 (0%) | 2 (22%) | 4 (18%) | 4 (27%) |
| Immunosuppressant prior to biopsy** | 55 (61%) | 8 (62%) | 6 (67%) | 2 (50%) | 17 (71%) | 7 (44%) | 7 (58%) | 5 (100%) | 5 (56%) | 15 (68%) | 9 (60%) |
| Taking immunosuppressant during biopsy† | 49 (56%) | 6 (55%) | 5 (63%) | 1 (33%) | 16 (67%) | 7 (44%) | 6 (50%) | 4 (100%) | 4 (44%) | 17 (81%) | 6 (40%) |
| Corticosteroids during biopsy** | 42 (47%) | 4 (31%) | 3 (33%) | 1 (25%) | 14 (58%) | 6 (38%) | 6 (50%) | 4 (80%) | 3 (33%) | 14 (64%) | 5 (33%) |
| Days from the onset of symptoms to the biopsy, median Q1–Q3 | 290 (117–615) | 721 (531–874) | 721 (599–1022) | 654 (275–802) | 270 (92–561) | 125 (66–293) | 163 (58–402) | 403 (296–637) | 232 (114–1880) | 497 (291–874) | 435 (289–919) |