In six patients with the diagnosis of polymyositis (PM) or dermatomyositis (DM) the authors used repeatedly whole-body scintigraphy of the skeleton using methylene diphosphonate labelled with the radionuclide 99m Tc ( 99m Tc-MDP). The administered radiopharmaceutical cumulates under certain conditions in soft tissues, e.g. in PM and DM (combination of degenerative and inflammatory changes). Based on the cumulation in soft tissues it is possible to detect the most severely affected area on which then further examinations can be focused (magnetic resonance, aimed biopsy). The change of cumulation of the radiopharmaceutical in soft tissues during repeated scintigraphic examinations indicates the therapeutic effect.

        Key words: polymyositis - dermatomyositis - whole-body bone scintigraphy - 99m Tc-MDP - visualiza-