Amyloid-like IgM deposition neuropathy with multiple mononeuropathies and generalized neuropathy

Pannathat Soontrapa, Christopher J. Klein, P. James B. Dyck, Sarah E. Berini, Ellen D. McPhail, Moritz Binder, Pitcha Chompoopong, Ja Nean Engelstad, Kamal Shouman

Research output: Contribution to journalArticlepeer-review


Amyloid-like IgM deposition neuropathy is a distinct entity in the setting of IgM monoclonal gammopathy in which endoneurial perivascular entire IgM-particle accumulation leads to a painful sensory followed by motor peripheral neuropathy. We report a 77-year-old man presenting with progressive multiple mononeuropathies starting with painless right foot drop. Electrodiagnostic studies showed severe axonal sensory-motor neuropathy superimposed by multiple mononeuropathies. Laboratory investigations were remarkable for biclonal gammopathy of IgM kappa, IgA lambda and severe sudomotor and mild cardiovagal autonomic dysfunction. A right sural nerve biopsy showed multifocal axonal neuropathy, prominent microvasculitis, and prominent large endoneurial deposits of Congo-red negative amorphous material. Laser dissected mass spectrometry-based proteomics identified IgM kappa deposit without serum amyloid-P protein. This case has several distinctive features, including motor preceding sensory involvement, prominent IgM-kappa proteinaceous deposits replacing most of the endoneurium, a prominent inflammatory component, and improvement of motor strength after immunotherapy.

Original languageEnglish (US)
Pages (from-to)391-395
Number of pages5
JournalNeuromuscular Disorders
Issue number5
StatePublished - May 2023
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2023 Elsevier B.V.


  • Amyloid-like IgM deposition neuropathy
  • IgM monoclonal gammopathy
  • Microvasculitis
  • Waldenstrӧm's macroglobulinemia

PubMed: MeSH publication types

  • Case Reports


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