Abstract |
Inclusion body myositis (IBM) is the most common acquired myopathy in adults older than 50 years. Muscle biopsy remains the gold standard for diagnosis. Recently described serum antibodies against cytosolic 5-nucleotidase 1A (cN1A) are considered highly specific for IBM. However, positive cN1A antibodies in diseases other than IBM are recently reported. We review 2 cases in which serum antibodies were positive but ancillary testing revealed motor neuron disease. A 68-year-old man presented with asymmetric quadriceps and handgrip weakness prompting concern for IBM. However, electromyography showed purely chronic neurogenic abnormalities, and muscle biopsy was consistent with post-polio syndrome. A 60-year-old woman reported a history of progressive muscle weakness. Despite positive antibodies, examination and electromyography were indicative of amyotrophic lateral sclerosis. Serum cN1A antibodies are not 100% specific for the diagnosis of IBM. Careful clinical, electrophysiologic, and histopathologic correlation is required in workup of individuals with neuromuscular weakness and positive antibodies.
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Authors | Rami-James K Assadi, Georgios Manousakis |
Journal | Journal of clinical neuromuscular disease
(J Clin Neuromuscul Dis)
Vol. 22
Issue 1
Pg. 50-52
(Sep 2020)
ISSN: 1537-1611 [Electronic] United States |
PMID | 32833724
(Publication Type: Case Reports, Journal Article)
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Chemical References |
- Autoantibodies
- 5'-Nucleotidase
- NT5C1A protein, human
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Topics |
- 5'-Nucleotidase
(blood)
- Aged
- Amyotrophic Lateral Sclerosis
(blood, diagnosis)
- Autoantibodies
(blood)
- Electromyography
- Female
- Hand Strength
- Humans
- Male
- Middle Aged
- Motor Neuron Disease
(blood, diagnosis)
- Muscle Weakness
(pathology)
- Muscle, Skeletal
(pathology)
- Myositis, Inclusion Body
(blood, diagnosis)
- Sensitivity and Specificity
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