Igg4-Related Kidney Disease
A rare renal disease occurring in the setting of a systemic IgG4 related disease (IgG4-RD). The disorder is characterized by a fibrosing tubulointerstitial nephritis consisting of predominantly IgG4+ plasma cells with/without glomerulonephritis, mass lesions, enlarged kidneys and hydronephrosis.
Epidemiology
The disease prevalence is unknown.
Clinical description
The clinical manifestations include tubulointerstitial nephritis (TIN) and membranous glomerulonephritis with or without TIN. Other glomerular disease is reported (IgA nephropathy, membranoproliferative glomerulonephritis, mesangioproliferative glomerulonephritis). Radiological abnormalities include mass lesions and diffusely enlarged kidneys. Presentation may be on routine imaging, with acute or chronic kidney disease, or with nephrosis depending on underlying lesion. Hydronephrosis may occur due to obstruction from IgG4-related retroperitoneal fibrosis. Other extra renal manifestations of IgG4-RD may also be present (e.g. salivary glands, hepatobiliary system, lungs).
Etiology
The etiology is unknown.
Diagnostic methods
The disease is diagnosed with characteristic imaging and renal biopsy findings (lymphocytic infiltration with predominantly IgG4+ plasma cells, storiform fibrosis, and obliterative phlebitis). Diagnostic criteria have been outlined.
Differential diagnosis
The differential diagnosis depends on presentation. For example, the differential for presentation with TIN includes: medications, autoimmune disease (e.g. Sjogren's syndrome, Sarcoid), malignancy (e.g. lymphoproliferative disease), and infection (e.g. Tuberculosis).
Management and treatment
Not supported by randomized controlled trials. Lymphocytic infiltration is usually quickly responsive to steroids. Steroid sparing agents are required/used in some patients.
Prognosis
Relapse is common, and progressive renal impairment can occur, including the need for renal replacement therapy.