What is IgG4-related disease (IgG4-RD)?
Key points about IgG4-RD and kidneys.
So. What is IgG4-related disease (IgG4-RD)?
IgG4-related disease (IgG4-RD), a recently recognised systemic inflammatory disorder, generally presents as a mass-forming lesion, or lesions, or organ enlargement
It is characterised by tissue infiltration with lymphocytes and IgG4-secreting plasma cells (IgG4+PC), various degrees of fibrosis (scarring) and a usually prompt response to oral steroids. In approximately 50–70% of people with this disease, serum IgG4 concentrations are elevated during an acute phase.
Clinical symptoms
Clinical symptoms are diverse depending on the combination of organs affected, but most patients have only mild or no symptoms.
Pathology
The most important feature is marked IgG4-positive plasma cell infiltration in affected organs. In addition, it has common histopathological features: dense lymphoplasmacytic infiltrates, storiform fibrosis and obliterative phlebitis.
Organs involved
Lacrimal and salivary glands, pancreas, kidneys and aorta/retroperitoneum are frequently affected organs. Patients often have multiple organ involvement simultaneously and sometimes at different times, and spontaneous regression has been observed.
Target organs are summarised here.
Organs that can be affected by IgG4-related disease
IgG-4 and the kidneys
The kidney is a representative organ, and the various renal lesions are collectively referred to as IgG4-related kidney disease (IgG4-RKD). Tubulointerstitial nephritis (TIN) is a typical lesion of the renal parenchyma, named IgG4-related TIN (IgG4-TIN), and renal pyelitis is typical of the renal pelvis.
IgG4-related retroperitoneal fibrosis can also induce renal insufficiency through hydronephrosis.
Other resource
These are good review articles: Salvadori, 2018, Evans, 2019, Capecchi, 2021 (case studies) and Kawano, 2023
Last Reviewed on 19 March 2024