LAUSR

A 1-year-old Japanese boy (Case 1) was referred to our hospital because of muscle weakness and skin ulcers. At the age of 1 year, he lost the ability to walk, although he had started to walk at 11 months. The patient exhibited proximal muscle weakness and muscle grasping pain. The serum creatine kinase level was increased to 136 IU/L (reference range, 41e123 IU/L), erythrocyte sedimentation rate was elevated to 36 mm/h (reference range, 1e10 mm/h), and anti-Jo-1 antibody was positive; magnetic resonance imaging indicated possible myositis of both the femoral muscles. Muscle biopsy revealed histological evidence of a mononuclear inflammatory infiltrate with a perivascular distribution. Furthermore, the patient was noted to have heliotrope rash, Gottron papules, and skin ulcers in the axillary areas (Figure 1). This patient fulfilled two diagnostic criteria for dermatomyositis (Bohan and Peter criteria: definite, and Japan criteria: definite). Accordingly, the patient was diagnosed with juvenile dermatomyositis (JDM). A 2-year-old Japanese girl (Case 2) was referred to our hospital because of muscle weakness and skin ulcers. At the age of 2 years, she lost the ability to walk, although she had