Amyloid Myopathy: A Cunning Masquerader

Amyloid myopathy (AM) is a rare manifestation of systemic amyloidosis (AL) or isolated amyloid myopathy, based on which the clinical features can vary. AM can have overlapping features with idiopathic inflammatory myopathies, and a muscle biopsy with Congo red staining is essential to differentiate between both. Other investigations, including a comprehensive myositis panel, magnetic resonance imaging (MRI) of the involved muscle group, and echocardiography, can also be beneficial. Treatment is based on the type of amyloid protein deposited and other organ involvement. This article reports a 74-year-old female with multiple features suggestive of antisynthetase syndrome, which, upon further workup, was proven to be a challenging case of amyloid myopathy secondary to immunoglobulin light chain AL.