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IgG4-related Disease Affecting Multiple Organs Despite Normal Serum IgG4 Levels
Takahiro Kida1, Kentaro Watanabe1, Mana Nishikawa1
1Department of Nephrology, Kurashiki Central Hospital, Japan.
Internal Medicine (Tokyo, Japan)
|May 24, 2026
Summary
Immunoglobulin G4-related disease (IgG4-RD) can affect multiple organs. Histopathology is crucial for diagnosis, especially when serum IgG4 levels are normal.
Area of Science:
- Nephrology
- Rheumatology
- Pathology
Background:
- Immunoglobulin G4-related disease (IgG4-RD) typically presents with elevated serum IgG4 levels.
- IgG4-RD is a multi-organ autoimmune condition.
- Diagnosis often relies on elevated IgG4 levels and characteristic histopathological findings.
Purpose of the Study:
- To present a case of IgG4-RD with normal serum IgG4 levels.
- To emphasize the role of histopathology in diagnosing IgG4-RD.
- To illustrate the effectiveness of corticosteroid therapy in such cases.
Main Methods:
- Case report presentation.
- Review of clinical presentation, laboratory findings, and imaging.
- Histopathological examination of affected tissues (kidneys, submandibular gland).
Main Results:
- A patient presented with IgG4-RD affecting kidneys, submandibular gland, lungs, lymph nodes, and retroperitoneum.
- Serum IgG4 levels were normal.
- Histopathology revealed lymphoplasmacytic infiltration with fewer IgG4-positive plasma cells than expected.
- The patient responded well to corticosteroid treatment.
Conclusions:
- Histopathological evaluation is essential for diagnosing IgG4-RD, particularly in cases with normal serum IgG4 levels.
- IgG4-RD can manifest with normal serum IgG4 levels, challenging initial diagnosis.
- Corticosteroid therapy remains effective for IgG4-RD, even in atypical presentations.
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