IgG4-related disease: a systemic condition with characteristic microscopic features.

Area of Science:

• Immunology
• Pathology
• Rheumatology

Background:

• Immunoglobulin G4-related disease (IgG4-RD) is a recently identified systemic fibroinflammatory condition.
• Elevated serum and tissue levels of Immunoglobulin G4 (IgG4) are characteristic of IgG4-RD.
• Autoimmune pancreatitis (AIP) was an early recognized manifestation, with subsequent identification of numerous extrapancreatic sites.

Purpose of the Study:

• To review the microscopic features of IgG4-related disease (IgG4-RD).
• To discuss the diagnosis and differential diagnosis of various organ manifestations of IgG4-RD.
• To address current concepts regarding the pathogenesis of IgG4-RD.

Main Methods:

• Review of histological findings in biopsies and resection specimens from affected organs in IgG4-RD.
• Analysis of common microscopic features across different IgG4-RD manifestations.
• Synthesis of current literature on IgG4-RD pathogenesis, diagnosis, and differential diagnosis.

Main Results:

• Common microscopic features of IgG4-RD include cellular and storiform fibrosis, lymphoplasmacytic infiltration, increased IgG4-positive cells, and obliterative phlebitis.
• These histological changes are observed irrespective of the affected organ site.
• IgG4-RD encompasses a spectrum of conditions, including AIP and formerly distinct fibroinflammatory lesions.

Conclusions:

• IgG4-RD is a systemic disease with characteristic histological findings across multiple organs.
• Accurate diagnosis relies on recognizing these microscopic features and considering the clinical context.
• Further research is needed to fully elucidate the etiology, pathophysiology, epidemiology, and long-term outcomes of IgG4-RD.