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Amyloidosis causing a progressive myopathy
N Nadkarni1, M Freimer, J R Mendell
1Department of Neurology, College of Medicine, Ohio State University, Columbus 43210, USA.
Muscle & Nerve
|September 1, 1995
Summary
Primary systemic amyloidosis can cause progressive myopathy, leading to profound muscle weakness. This condition is pathologically distinct from inclusion body myopathies, featuring extracellular amyloid deposits around muscle fibers.
Area of Science:
- Neurology
- Pathology
- Biochemistry
Background:
- Primary systemic amyloidosis is a rare condition characterized by amyloid protein deposition in various organs.
- Progressive myopathy can be a debilitating manifestation of systemic amyloidosis, impacting muscle function.
- Distinguishing amyloid myopathy from other myopathies is crucial for accurate diagnosis and treatment.
Observation:
- A 62-year-old woman presented with severe muscle weakness due to progressive myopathy.
- Pathological examination revealed extracellular amyloid deposits surrounding muscle fibers, confirmed by Congo red staining (apple-green birefringence).
- Electron microscopy showed amyloid filaments adjacent to muscle fibers with significant sarcolemmal membrane corrugations.
Findings:
- The observed myopathy was directly associated with primary systemic amyloidosis.
- Amyloid deposits were extracellular, surrounding muscle fibers, a key diagnostic feature.
- These pathological findings differ significantly from the intracellular amyloid seen in inclusion body myositis.
Implications:
- This case highlights the distinct pathological features of amyloid myopathy in primary systemic amyloidosis.
- Understanding these distinctions is vital for differentiating amyloid myopathy from other myopathies like inclusion body myositis.
- Accurate pathological characterization aids in patient management and understanding disease progression.