A French-Canadian team analysed some sixty publications in order to better define the diagnostic criteria for scleromyositis, an emerging entity. Their review highlights in particular :
- muscle weakness that is often symmetrical and proximal, more important in the upper than in the lower limbs, axial, more rarely distal ;
- an increase in CKemia;
- numerous possible extra-muscular and extra-cutaneous attacks, the most frequent of which are respiratory, cardiac, vascular, tendino-articular, and renal, such as scleroderma renal crisis (SRC);
- a positive association between scleromyositis and anti-PM/Scl, anti-Ku, anti-U1RNP, anti-U3RNP, anti-RuvBL1/2, anti-SMN autoantibodies, but almost half of the patients are seronegative;
- specific vasculopathy lesions on muscle biopsy, such as basement membrane duplication (four or more layers in more than 50% of capillaries).
The treatment of scleromyositis is, to date, not consensual. However, corticosteroid therapy is thought to increase the risk of CRS. And certain aspects of the muscle biopsy (necrosis, fibrosis) would be predictive of the response to immunomodulators.
