Table 1. Clinical Features, Myopathological Findings, and Autoantibodies.
| Characteristic | No. (%) | P value | |
|---|---|---|---|
| With skin rash (n = 168) | Sine dermatitis (n = 14) | ||
| Female | 85 (51) | 8 (57) | .64 |
| Age at biopsy, median (IQR), y | 55 (46) | 60 (30) | .44 |
| Clinical features | |||
| Rash of typical dermatomyositis | 132 (79) | 0 | NA |
| Gottron sign | 119 (71) | 0 | NA |
| Heliotrope | 81 (48) | 0 | NA |
| Shawl sign | 48 (29) | 0 | NA |
| V-sign | 36 (21) | 0 | NA |
| Periungual erythema | 33 (20) | 0 | NA |
| Other skin rasha | 147 (88) | 0 | NA |
| Muscle weakness | 150 (89) | 14 (100) | .20 |
| Myalgia | 119 (71) | 13 (93) | .08 |
| Dysphagia | 59 (35) | 7 (50) | .27 |
| Interstitial lung disease | 28 (17) | 1 (7) | .35 |
| Malignancy | 35 (21) | 2 (14) | .56 |
| Examination results | |||
| CK, median (IQR), U/L | 826 (262-4477) | 1179 (750-1987) | .52 |
| KL-6, median (IQR), U/mLb | 278 (203-400) | 305 (243-444) | .32 |
| Myogenic change in electromyographyb | 94 (87) | 12 (100) | .18 |
| Myopathologic findings | |||
| Perifascicular atrophy | 73 (43) | 10 (71) | .04 |
| Microinfarction | 26 (15) | 2 (14) | .91 |
| Perifascicular MHC class I reinforcement | 89 (53) | 9 (64) | .42 |
| MHC class II expression | 22 (13) | 3 (21) | .38 |
| MAC deposition on capillaries | 151 (90) | 13 (93) | .72 |
| Autoantibodies positivity | |||
| TIF1-γ | 64 (38) | 1 (7) | .02 |
| Mi-2 | 25 (15) | 1 (7) | .43 |
| MDA5 | 22 (13) | 0 | .15 |
| NXP-2 | 47 (28) | 12 (86) | <.001 |
| SAE | 4 (2) | 0 | .56 |
Abbreviations: CK, creatinine kinase; IQR, interquartile range; KL-6, Krebs von den Lungen-6; MAC, membrane attack complex; MDA5, melanoma differentiation-associated gene 5; MHC, human major histocompatibility complex; NA, not applicable; NXP-2, nuclear matrix protein 2; SAE, small ubiquitin-like modifier activating enzyme; TIF1-γ, transcription intermediary factor 1 γ.
SI conversion factor: To convert creatinine kinase to microkatals per liter, multiply by 0.0167.
a
Other skin rashes are all kinds of rashes except for typical DM skin rashes, such as nailfold punctuated hemorrhage, seborrheic eczema, butterfly rash, and nonspecific rash.
b
The denominator of the percentage indicates the total number of nonmissing responses.