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AL amyloidosis presenting with isolated lumbosacral radiculoplexus neuropathy
  1. Roberto Bellanti1,
  2. Mkael Symmonds1,2,
  3. Rajat Chowdhury3,
  4. Monika Hofer1,4,
  5. Simon Rinaldi1
  1. 1Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
  2. 2Department of Clinical Neurophysiology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
  3. 3Department of Musculoskeletal Radiology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
  4. 4Department of Neuropathology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
  1. Correspondence to Dr Simon Rinaldi, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; simon.rinaldi{at}


A 45-year-old man presented with an isolated sciatic mononeuropathy, which then evolved into a lumbosacral radiculoplexus neuropathy. His initial symptoms included lower limb pain, sensory disturbance and later weakness, without autonomic dysfunction. Neurophysiology suggested a postganglionic neuropathy. MR and ultrasound scans of the thighs showed right sciatic nerve thickening, and CSF analysis showed albuminocytological dissociation. Fluorodeoxyglucose positron emission tomography (FDG PET) was unremarkable. He then developed orthostatic symptoms and urinary disturbance, and was found to have an IgM paraprotein. Fat aspirate, cardiac and whole-body imaging found no amyloid deposition, and genetic testing for transthyretin amyloidosis was negative. A bone marrow biopsy was unremarkable. However, neuropathology review of a proximal, fascicular nerve biopsy identified a lambda chain-restricted plasma cell population with positive Congo red staining, leading to a diagnosis of peripheral nerve restricted amyloid light amyloidosis. We discuss the diagnostic approach to this case from the perspectives of neurology, neurophysiology, radiology and neuropathology.

  • neuropathy
  • peripheral neuropathology
  • amyloid
  • neurophysiology
  • neuroradiology

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  • Contributors RB and SR wrote the original draft of the manuscript. MS, RC and MH contributed to subsequent drafts and revisions. All authors approved the final version.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned. Externally peer reviewed by Alex Rossor, London, UK.

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