[Immunocytochemical study of the inflammatory forms of facioscapulohumeral myopathies and correlation with other types of myositis].

The inflammatory forms of facioscapulohumeral myopathies are rare. In a series of 52 cases, six patients had these types. Only four cases could be investigated with immunochemical staining (immunoperoxidase). Monoclonal antibodies reactive for B cells, T4 cells, T8 cells, natural killer cells were used for cell typing. Macrophages were identified by the acid phosphatase reaction. Nine muscles have been used as controls: 3 normal muscles, 3 polymyositis and 3 dermatomyositis. In all these inflammatory myopathies T cells were the most abundant cells. NK cells were rare. In inflammatory FSH-D and in polymyositis the infiltrates were principally endomysial, whereas T8 lymphocytes were more abundant than T4 lymphocytes; it was the contrary in the perivascular and perimysial sites of accumulation. In dermatomyositis the infiltrates were especially perivascular. In this site of accumulation T4 was twice abundant than T8, B cells and macrophages were also very abundant. In the endomysium the T8 cells were more numerous than T4 cells. It seems that the inflammatory forms of FSH-D should be considered as an inflammatory myopathy. In these forms a polymyositis should be associated with the dystrophy. These forms could be considered as an association of a polymyositis and a muscular dystrophy, but the circumstances of their appearance and their non-response to corticosteroid administration remain to be determined.