Ultrasonographic features of IgG4-related kidney disease: diagnostic value and correlation with clinical-pathological...

To systematically characterize the ultrasonographic features of biopsy-proven IgG4-related kidney disease (IgG4-RKD) and to evaluate their correlation with key clinicopathological parameters.

In this retrospective study, the ultrasonographic, clinical, laboratory, and pathological data of 15 patients with biopsy-confirmed IgG4-RKD were analyzed. Key sonographic features, including renal size, parenchymal echotexture, focal lesions, and resistive index, were evaluated and correlated with clinicopathological findings.

The cohort consisted of predominantly older males (86.7%) with frequent multi-organ involvement (60.0%). The most common ultrasonographic pattern included bilateral involvement (93.3%), increased or heterogeneous echogenicity (73.3%/60.0%), multiple hypoechoic areas (46.7%), and enlargement of at least one kidney (>12 cm) in 40.0% of patients. Increased renal length showed a significant positive correlation with serum IgG4 levels (r = 0.63, 95% confidence interval (CI) [0.17, 0.86], p < 0.05), and parenchymal thickness showed a significant negative correlation with serum C3 levels (r = -0.58, 95% CI [-0.84, -0.10], p < 0.05). Furthermore, parenchymal thickness was moderately correlated with serum creatinine (r = 0.51, n = 15, 95% CI [0.00, 0.81], p < 0.05). Ultrasound also effectively monitored therapeutic response, with 83.3% of followed patients showing structural improvement.

Ultrasonography in IgG4-RKD reveals a characteristic pattern of findings that not only serve a descriptive role but also quantitatively correlate with serological disease activity and renal dysfunction. Therefore, ultrasound is a valuable, non-invasive tool for initial assessment, guiding diagnosis, and monitoring therapeutic response in the clinical management of IgG4-RKD.