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Case Reports
. 2023 May 27;15(5):e39576.
doi: 10.7759/cureus.39576. eCollection 2023 May.

Amyloid Myopathy: A Cunning Masquerader

Guru Prasad Parthiban  1 , Jon Wilson  2 , Joseph Nesheiwat  3
Affiliations
Case Reports

Amyloid Myopathy: A Cunning Masquerader

Guru Prasad Parthiban et al. Cureus. .

Abstract

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.

Keywords: al amyloid; immunoglobulin light-chain amyloidosis; monoclonal gammopathy; pelvic girdle myopathy; systemic amyloid.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. CT chest showing bilateral basal atelectasis
Figure 2
Figure 2. Muscle biopsy showing regenerating muscle fibers without evidence of myonecrosis
Figure 3
Figure 3. Polarized light imaging demonstrating apple-green birefringence of vascular amyloid deposits
Figure 4
Figure 4. Immunofluorescence microscopy with positive lambda light chain
See this image and copyright information in PMC

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