IgG4-related kidney disease complicated with retroperitoneal fibrosis: A case report

Figure 1 Enhanced computed tomography of the total abdomen suggested retroperitoneal fibrosis. A and B: At the abdominal aorta, the furcation of the iliac artery, middle sacral artery, bilateral common iliac arteries and inferior vena cava were encysted by the front soft tissue mass; C and D: The middle piece of both ureters was narrowed. The upper section of the bilateral ureters was dilated, and there was mild hydronephrosis of both kidneys.

Figure 2 Histopathological findings on the kidney biopsy. A: The renal interstitium was infiltrated by plasma cells and lymphocytes predominantly with fibrosis like car width [light microscopy: Hematoxylin and eosin (HE), × 100]; B: The injury of the glomerular lesion was mild [light microscopy: Periodic acid-Schiff staining, × 400]; C: Glomerular sclerosis and striate fibrosis in the renal interstitium [light microscopy: Masson and periodic acid-sliver methenamine, × 400]; D: Masson 200 staining of the lesion that was the same as that in Figure A; E and F: Most fusion of glomerular podocytes was observed by electron microscopy, while no electron dense granules were observed in the subepithelium, mesangial area, or subendothelium; G and H: IgG4 plasma cells > 10 cells/high powered field and IgG4 plasma cells/IgG plasma cells > 40% were observed by immunohistochemistry; I: There were CD38-positive plasma cells and CD138-positive plasma cells.

Figure 3 Variation trend of creatinine after admission. As shown in the upper line chart, creatinine (Cr) decreased continuously after glucocorticoid treatment. After 19 mo of follow-up, Cr decreased from 1148.6 µmol/L during hospitalization to 154.9 µmol/L at his visit on November 26, 2022.

Figure 4 Disease spectrum of IgG4-related disease. IgG4-related disease involves multiple systems, including the kidney, while IgG4-related tubulointerstitial nephritis is the most common. The main manifestations of retroperitoneal fibrosis (IgG4-RPF) or idiopathic retroperitoneal fibrosis are local compressive symptoms and dysfunction of the involved organs. For example, IgG4-RPF may cause obstructive nephropathy, causing edema of both lower limbs.