Skeletal muscle pathology in 2 siblings infected with Toxoplasma gondii

Skeletal muscle can be the site of inflammatory diseases that lead to muscle weakness, pain, and increased myogenic serum enzymes. Most of these inflammatory myopathies are idiopathic. In some cases inflammatory myopathies are due to infectious agents. We describe the pathological aspects of muscle biopsies of 2 Brazilian siblings who acquired toxoplasmosis at the same time and in similar conditions. One developed a tetraplegia that was confirmed to be due to inflammatory myositis due to toxoplasma. The other developed myocarditis, with heart failure, without skeletal muscle weakness. In both cases many toxoplasma organisms were observed in the muscle biopsies, but in case 1 only was there an inflammatory myopathy with myofiber necrosis; the inflammatory cells were predominantly macrophages with some CD4+ cells and rare CD20+ cells. In case 1, expression of CD54 was observed in many inflammatory cells as well in endothelial cells, but only in endothelial cells in case 2. After treatment with clindamycin and corticosteroids both cases had only partial improvement, case 1 with a residual muscle weakness and case 2 with residual cardiac insufficiency (requiring digoxin). These cases show that the presence of the parasite in myofibers is not enough to induce an inflammatory myositis with muscle cell necrosis. This suggests that immunological disturbances may contribute to the development of inflammatory myositis due to toxoplasma.