Proximal muscle weakness and skin rash.

A 34 year old woman presented with a 9 day history of progressive proximal bilateral limb weakness and mild dysphagia with fluids. On examination, she had a peri-orbital rash (fig 1). Neurological findings included moderately severe (grade 3-4/5) bilateral proximal limb and neck flexor weakness with preserved deep tendon reflexes and sensation.Fig. 1 Peri-orbital rashHer laboratory test findings wereFat suppressed magnetic resonance imaging (MRI) of the thigh muscles showed abnormal signals (hyperintensities) of the lateral, medial, and anterior compartments (fig 2).Fig. 2 Magnetic resonance imaging (MRI) (fat suppressed short tau inversion recovery image) of the thigh muscles. (Left) Coronal section, (right) axial sectionNeedle electromyography of the proximal arm and leg muscles showed fibrillation, positive sharp waves, and early recruitment of volitional motor unit potentials.### 1. What is the diagnosis?Dermatomyositis—an inflammatory disorder involving the skin and muscles. Figure 1 shows dusky bilateral erythematous macular rashes in the slightly swollen peri-orbital regions. This is a heliotrope rash and is characteristic of dermatomyositis.12 The patient’s proximal limb weakness, mild dysphagia, preserved deep tendon reflexes, elevated creatine kinase, MRI findings (fig 3), and needle electromyography findings are also suggestive of myopathy.34Fig. 3 Magnetic resonance imaging (MRI) (fat suppressed short tau inversion recovery image) of the thigh muscles. (Left, A) Coronal section, (B, right) axial section. Hyperintensities (stars) …