Teaching neuroimages: hydroxychloroquine-induced vacuolar myopathy.

Abstract

A 58-year-old woman with long-standing mixed connective tissue disorder had proximal leg weakness for 4 months. She had been treated with 400 mg/day of hydroxychloroquine and varying doses of prednisone over 15 years. Creatine kinase was 600 U/mL. MRI of quadriceps showed edema and its biopsy revealed myriad acid-phosphatase–positive autophagic vacuoles indicating increased lysosomal activity (figure). Hydroxychloroquine induces autophagy by reducing lysosomal acidity.¹ Autophagic vacuolar myopathy can be seen with chloroquine or colchicine therapy or in inherited disorders (α-glucosidase deficiency, Danon disease, and X-linked myopathy with excessive autophagy).¹ Hydroxychloroquine myopathy usually presents with mild to moderate proximal weakness and rarely causes severe weakness and respiratory failure.² Our patient's weakness improved after discontinuing hydroxychloroquine.