42-year-old man with discoid lupus and progressive weakness

A 42-year-old man presented with three months of progressive proximal weakness, a thirty pound weight loss, and dysphagia. He was hospitalized two months earlier for ventilatory failure requiring five days of mechanical ventilation. His history also included long-term hydroxychloroquine therapy for discoid lupus and a recently elevated total creatine kinase. An electromyogram revealed evidence of an irritable myopathy. Microscopic examination of a muscle biopsy specimen revealed vacuolar myopathy with lysosomal activation. Electron microscopy demonstrated curvilinear inclusions that, given his history, were diagnostic of hydroxychloroquine (HCQ) myopathy. Although HCQ myopathy typically presents with proximal muscle weakness and normal-to-mildly-elevated creatine kinase levels, this is one of the few reported cases of ventilatory failure due to HCQ myopathy. Hydroxychloroquine myopathy may be more common than previously reported and should be considered in patients on long term therapy presenting with weakness or ventilatory failure. In these cases, muscle biopsy should be performed to confirm the diagnosis.