[Possible Diagnosis of Segmental Ureteritis Due to an IgG4-Related Disease that Improved with Steroid Therapy].

A 70-year-old woman was referred to our department after being diagnosed with right hydronephrosis on the basis of computed tomography (CT). CT and magnetic resonance imaging results indicated circumferential wall thickening in the right middle ureter. A retrograde pyelogram revealed an approximately 20 mm stricture in the right middle ureter, and urine cytology results were pseudo-positive. Ureteroscopy was performed due to suspicion of a malignant tumor of the urinary tract, but no malignant lesions were found. Biopsy results showed only the pathology of nonspecific ureteritis, and a diagnosis could not be made even with immunostaining. The patient's blood IgG4 levels were high (317 mg/dl). Based on the diagnostic criteria, the patient was given a possible diagnosis of an IgG4-related disease and treated by the placement ofa ureteral stent and administration of steroid therapy. After starting treatment, blood IgG4 levels decreased and the imaging findings showed improvement. The ureteral stent was removed in the 12th week, and steroid administration was discontinued in the 14th week. No recurrence has since been noted.