Steroid‐responsive myopathy with deficient chondroitin sulfate C in skeletal muscle connective tissue

Abstract

A 71-year-old man developed severe limb, bulbar, and respiratory weakness over 18 months. A muscle biopsy showed only a moderate degree of type 2 atrophy, but immunocytochemistry showed absence of chondroitin sulfate C glycosaminoglycan in the endomysium. Prednisone produced a marked increase in strength. Diffuse loss of endomysial chondroitin sulfate C was a feature of this treatable myopathy with severe weakness, but few pathologic changes.