Primary localized amyloidosis of the ureter presenting as a ureteral stone

Primary localized amyloidosis of the urinary tract is a rare disease, usually mimicking a malignancy or inflammation in its clinical presentation and in diagnostic imaging studies. We present a case of localized amyloidosis arising in the left upper ureter in a 77-year-old man. The patient visited the hospital complaining of painless gross hematuria and dysuria for 1 month. Laboratory examination revealed hematuria only. Urine cytology was unremarkable. Abdominal computed tomography revealed an obstructing mass with calcification in the ureter. The clinical impression was of a ureteral stone or malignancy. A nephroureterectomy was performed. The ureter showed segmental fibrotic thickening with luminal obstruction. Microscopic examination revealed deposition of pale-eosinophilic amorphous material with calcification and ossification. Congo-red staining showed amyloid deposits with positive polarizing microscopic findings. Although its incidence is rare, localized amyloidosis should be considered in the differential diagnosis of ureteral tumorous lesions to avoid unnecessary surgery.