Thrombotic microangiopathy in juvenile dermatomyositis

Objectives and study A 4year-old boy was admitted to our hospital because of progressive proximal muscular weakness of 4 weeks duration, heliotrope rash, erythematous skin lesions in the trunk and limbs and febrile fever. The muscle enzymes were elevated: creatine kinase 7,056 IU/L (0– 170), aldolase 40.3 U/L (0–8), aspartate transaminase 601 U/L (10–37), alanine transaminase 289 U/L (10–37). The laboratory test revealed a hemoglobin level of 86 g/dL, a platelet count of 100,000/mm3, an erythrocyte sedimentation rate of 30 mm/h . A peripheral blood smear revealed schistocytes (2%). Urine analysis revealed large number of red blood cells and proteinuria 1.06 grams / liter. The level of total serum bilirubin was 37 μmol / l (normal up to 17 μmol / l). Serum creatinine was 200 μmol/l. Direct and indirect Coombs’ reaction was negative. Prothrombin and thrombin time and D-dimers were within normal limits.The serologic tests for the antinuclear antibody, antineutrophil cytoplasmic antibody, antibodies to DNA, cardiolipin antibodies, antibodies to b2glycoproteins were negative. Lupus anticoagulant was not detected. The electromyographic findings were consistent with the inflammatory myopathy. A renal biopsy contained 43 glomeruli and was evaluated by light and immunofluorescence microscopies. Diffuse fibrin-platelet thrombi were revealed in glomerular capillaries. Small arteries was narrowed by the swelling of the endothelium. The expression of the fibrin + +. There were no immune deposits at any location.