Table 1.
Pathological and clinical features in subgroups of IIMs
| Subgroup | Myositis antibody | Histological features | IHC features | Clinical features | ||
| HLA-ABC | HLA-DR | C5b-9 | ||||
| DM | Anti-TIF1-γ | PFA, Punched-out vacuoles | + | -/+ | Capillaries>sarcolemma | CAM Skin erythema |
| Anti-Mi-2 | PFA, PFN, Promiment inflammation | + | -/+ | Sarcolemma>Capillaries | ||
| Anti-NXP2 | Microinfarction Muscle ischemia | + | -/+ | Capillaries>sarcolemma | JDM CAM Calcification | |
| Anti-MDA5 | Non-PFA | + | -/+ | Capillaries>sarcolemma | ADM | |
| Anti-SAE | PFA | + | -/+ | Capillaries | ILD | |
| ASS | Anti-Jo-1 | PFA Myofiber necrosis and regederation | + | +(PF) | sarcolemma | Myositis>ILD With Raynaud, Mechanic hands, Joint involvement |
| Anti-PL-7 | + | +(PF) | sarcolemma | ILD>myositis | ||
| Anti-PL-12 | + | +(PF) | sarcolemma | ILD>myositis | ||
| Anti-OJ | + | +(PF) | sarcolemma | Severe muscle involvement | ||
| IMNM | Anti-SRP | Myofiber necrosis and regeneration Less inflammation (macrophage>lymphocyte) | + | – | sarcolemma | Cardiac involvement |
| Anti-HMGCR | + | – | sarcolemma | |||
IIMs, idiopathic inflammatory myopathies; DM, dermatomyositis; ASS, anti-synthetase syndrome; IMNM, immune-mediated myopathy; anti-Mi-1, anti-complex nucleosome remodeling histone deacetylase antibodies; anti-MDA5, anti-melanoma differentiation associated gene 5 antibodies; anti-TIF1γ, anti-transcription intermediary factor 1 γ antibodies; anti-NXP2, anti-antinuclear matrix protein 2 antibodies; anti-SAE, anti-small ubiquitin-like modifier-activating enzyme antibodies; anti-SRP, anti-signal recognition particle antibodies; anti-HMGCR, anti-3-hydroxy-3-methylglutaryl coenzyme A reductase antibodies. PFA, perifascicular atrophy; PFN, perifascicular necrosis; IHC, immunohistochemistry.