OBJECTIVE: To evaluate the pathologic significance of immunoglobulin G4 (IgG4) in patients with inflammatory peripheral neuropathy. METHODS: We clinicopathologically examined 149 consecutive patients with peripheral neuropathy who had clusters of inflammatory cells with or without vasculitis in sural nerve biopsy specimens and in whom we were able to assess the serum IgG4 levels. RESULTS: Elevation of serum IgG4 levels and infiltration of IgG4-positive plasma cells, which are currently defined as the diagnostic criteria for IgG4-related disease, were found in 35 and 29 patients, respectively. In the 44 patients exhibiting either elevated serum IgG4 levels or IgG4-positive cell infiltration, the diagnoses prior to the examination of IgG4 in serum and pathologic samples included microscopic polyangiitis (12 patients) and eosinophilic granulomatosis with polyangiitis, or Churg-Strauss syndrome (19 patients). Thirty-four patients (77%) had findings of vasculitis as indicated by the destruction or obstruction of the vessel walls. Sixteen (36%) of these patients had fibrinoid necrosis. Axonal degeneration without evidence of demyelination was observed irrespective of the presence of vasculitis. The extent of fibrosis, assessed as the fibrotic area in the epineurium, significantly correlated with the grade of IgG4-positive cell infiltration (p < 0.01). CONCLUSIONS: Elevated serum IgG4 levels and infiltration of IgG4-positive plasma cells were observed in a subgroup of patients with inflammatory neuropathy, particularly in patients diagnosed with primary systemic vasculitis, including microscopic polyangiitis. Epineurial IgG4-positive plasma cell infiltration correlated with the extent of epineurial fibrosis.
OBJECTIVE: To evaluate the pathologic significance of immunoglobulin G4 (IgG4) in patients with inflammatory peripheral neuropathy. METHODS: We clinicopathologically examined 149 consecutive patients with peripheral neuropathy who had clusters of inflammatory cells with or without vasculitis in sural nerve biopsy specimens and in whom we were able to assess the serum IgG4 levels. RESULTS: Elevation of serum IgG4 levels and infiltration of IgG4-positive plasma cells, which are currently defined as the diagnostic criteria for IgG4-related disease, were found in 35 and 29 patients, respectively. In the 44 patients exhibiting either elevated serum IgG4 levels or IgG4-positive cell infiltration, the diagnoses prior to the examination of IgG4 in serum and pathologic samples included microscopic polyangiitis (12 patients) and eosinophilic granulomatosis with polyangiitis, or Churg-Strauss syndrome (19 patients). Thirty-four patients (77%) had findings of vasculitis as indicated by the destruction or obstruction of the vessel walls. Sixteen (36%) of these patients had fibrinoid necrosis. Axonal degeneration without evidence of demyelination was observed irrespective of the presence of vasculitis. The extent of fibrosis, assessed as the fibrotic area in the epineurium, significantly correlated with the grade of IgG4-positive cell infiltration (p < 0.01). CONCLUSIONS: Elevated serum IgG4 levels and infiltration of IgG4-positive plasma cells were observed in a subgroup of patients with inflammatory neuropathy, particularly in patients diagnosed with primary systemic vasculitis, including microscopic polyangiitis. Epineurial IgG4-positive plasma cell infiltration correlated with the extent of epineurial fibrosis.
Authors: Zachary M Dong; Edwin Lin; Michael E Wechsler; Peter F Weller; Amy D Klion; Bruce S Bochner; Don A Delker; Mark W Hazel; Keke Fairfax; Paneez Khoury; Praveen Akuthota; Peter A Merkel; Anne-Marie Dyer; Carol Langford; Ulrich Specks; Gerald J Gleich; Vernon M Chinchilli; Benjamin Raby; Mark Yandell; Frederic Clayton Journal: Am J Pathol Date: 2020-04-03 Impact factor: 4.307