Teenager with proximal muscle weakness and a heliotrope rash

MRI of dermatomyositis
Coronal (above) and axial (below left) T2 MRI of the pelvis along with axial T2 MRI of the thighs (below right) shows diffuse, bilateral, symmetrical bright signal in the visualized muscles representing intramuscular edema in the quadratus lumborum, gluteal, and proximal thigh hamstring muscles.

The diagnosis was dermatomyositis.