Dermatopathic Lymphadenopathy With Increased IgG4-Positive Plasma Cells

Area of Science:

• Immunopathology
• Lymph Node Biology
• Allergic Diseases

Background:

• Dermatopathic lymphadenopathy (DL) and immunoglobulin G4-related disease (IgG4-RD) are associated with allergic conditions.
• The precise relationship between DL and IgG4-RD remains unclear.
• Investigating IgG4-positive (IgG4+) plasma cell infiltration in DL lymph nodes (LNs) is crucial.

Purpose of the Study:

• To elucidate the relationship between DL and IgG4-RD.
• To analyze IgG4+ plasma cell infiltration in DL lymph nodes.
• To correlate pathological findings with clinical outcomes.

Main Methods:

• Immunohistochemical analysis of LNs from 11 DL patients for IgG, IgG4, FOXP3, TGF-β, IFN-γ, MMPs, and mast cells.
• Toluidine blue staining for mast cell identification.
• Correlation of LN findings with clinical development of IgG4-RD.

Main Results:

• Two of three patients with high IgG4+/IgG+ cell ratios (>40%) and elevated serum IgG4 developed IgG4-RD.
• Five of eight patients with low IgG4+/IgG+ ratios or no infiltration did not develop IgG4-RD.
• LNs with high IgG4+ cell infiltration showed increased mast cells and TGF-β, but no fibrosis; IFN-γ and MMPs were also detected.

Conclusions:

• DL with increased IgG4+ cells appears to be a lymph node manifestation of IgG4-RD.
• Mast cells may contribute to TGF-β production in DL.
• The presence of IFN-γ and MMPs might prevent fibrosis in DL lymph nodes.