Polyneuropathy in nonmalignant IgM plasma cell dyscrasia: a morphological study

Area of Science:

• Neurology
• Immunology
• Pathology

Background:

• Peripheral neuropathy can be associated with plasma cell dyscrasias.
• IgM plasma cell dyscrasia is a nonmalignant condition that can present with neurological complications.

Purpose of the Study:

• To investigate the underlying mechanisms of peripheral neuropathy in patients with IgM plasma cell dyscrasia.
• To determine if monoclonal immunoglobulins play a role in nerve damage.

Main Methods:

• Immunological studies to identify monoclonal immunoglobulin targets.
• Sural nerve biopsy for morphological examination.
• Analysis of clinical and pathological findings in six patients.

Main Results:

• Two patients had monoclonal immunoglobulin reacting with myelin-associated glycoprotein, with primary myelin sheath damage.
• Four patients showed primary axonal injury, with two having monoclonal IgMK reactive with chondroitin sulfate C.
• Heterogeneous patterns of nerve damage were observed.

Conclusions:

• The pathogenesis of peripheral neuropathies in IgM plasma cell dyscrasia is diverse.
• Monoclonal IgM paraproteins may interact with peripheral nerve autoantigens, contributing to neuropathy in some cases.