The classification of dermatomyositis (DM) has undergone profound changes since the identification of myositis-specific autoantibodies (MSA). Tokyo neuromuscular pathology specialists re-evaluated 256 muscle biopsies from patients with DM trying to establish correlations between histological lesions and immunological signatures:
- the positivity of the MxA staining, whether or not observed in the perivascular areas, was the main criterion for inclusion in the study,
- at the end of the screening by MSA, only seven cases of DM remained seronegative,
- correlations between histological lesions and MSA positivity have been established for most DM subtypes.