From the Guidelines
A CT scan with contrast of the abdomen and liver in a patient with IgG4-related kidney disease may show characteristic findings such as diffuse kidney enlargement, multiple low-density lesions in the kidneys, and biliary strictures in the liver, but a completely normal scan does not rule out the disease. The CT scan may reveal various abdominal and liver findings, including thickening of the renal pelvis wall, a rim of soft tissue around the kidneys, pancreatic enlargement, lymphadenopathy, and thickening of the walls of various organs 1. However, the accuracy of contrast-enhanced CT in establishing a definitive diagnosis is around 71% to 95% for differentiating between malignant and benign lesions, and additional imaging may be recommended in some cases 1.
In the context of IgG4-related kidney disease, a normal CT scan with contrast does not significantly reduce the likelihood of the disease, as some patients with early or limited disease may have normal imaging despite having the condition. The diagnosis of IgG4-related kidney disease typically requires a combination of clinical features, elevated serum IgG4 levels, and histopathological confirmation through biopsy showing characteristic findings such as lymphoplasmacytic infiltration, storiform fibrosis, and IgG4-positive plasma cell infiltration.
Some key points to consider when interpreting the CT scan results include:
- The sensitivity and specificity of contrast-enhanced CT for establishing a definitive diagnosis vary depending on the specific clinical scenario and the presence of underlying liver disease or extrahepatic malignancy 1.
- Multiphase contrast-enhanced CT has high accuracy for diagnosing certain liver lesions, such as hemangioma, focal nodular hyperplasia (FNH), and hepatocellular carcinoma (HCC) 1.
- The use of FDG-PET/CT or DOTATATE PET/CT is not supported by relevant literature for this clinical scenario 1.
Therefore, if clinical suspicion of IgG4-related kidney disease remains high despite a normal CT scan, further diagnostic workup including serum IgG4 measurement and possibly kidney biopsy should be considered.
From the Research
CT Scan with Contrast Findings in IgG4-Related Kidney Disease
A CT scan with contrast of the abdomen and liver in a patient with IgG4-related kidney disease may show:
- Multiple low-density lesions on contrast-enhanced computed tomography 2
- Diffuse thickening of the renal pelvic wall 2
- Masses in the kidney 3
- Abnormal radiographic findings, including masses in 30% of patients 3
Reduction in Likelihood of IgG4-Related Kidney Disease with Normal CT Scan
A completely normal CT scan with contrast of the abdomen and pelvis may reduce the likelihood of IgG4-related kidney disease, but it does not completely rule out the disease. Some patients with IgG4-related kidney disease may have normal imaging findings, and the disease can only be confirmed with a renal biopsy 3, 4, 5.
- 52% of patients with IgG4-related kidney disease had abnormal radiographic findings, but this means that 48% may have normal findings 3
- The clinical presentation of IgG4-related kidney disease is variable and can include acute or chronic kidney injury, proteinuria or nephrotic syndrome, mass lesion(s), and obstruction 5
- A normal CT scan should be considered in the context of other clinical and laboratory findings, such as serum IgG and IgG4 levels, and renal function tests 2, 6, 4