Masquerader in oncology: IgG4-related kidney disease presenting as right upper ureteric mass

Immunoglobulin G4-related disease (IgG4-RD) is a systemic immune-mediated fibroinflammatory condition that can mimic several diseases and can present as a malignant tumor. We present a case of a 53-year-old woman who presented with a right upper ureteric mass. On pathologic evaluation, a diagnosis of IgG4-RD was made. In the absence of preoperative biopsy and other clinical manifestations, preoperative clinical diagnosis remains challenging and high index of suspicion and accurate pathological evaluation may help in avoiding misdiagnosis.