Amyloid myopathy is one of the uncommon manifestations of systemic amyloidosis. The symptoms are usually nonspecific, typically including progressive proximal limb weakness with an increased creatine kinase level, macroglossia, and muscle pseudohypertrophy. It is often misdiagnosed as inflammatory myopathy, even when a muscle biopsy is available. When suspecting amyloid myopathy, Congo red staining and either an immunohistochemical assay or immunofluorescence study should be performed.
Oct. 16, 2020