[A case of malignant lymphoma originating from paraureteral tissue]

A 53-year-old man was admitted with epigastric discomfort. Excretory pyelography demonstrated left non visualizing kidney. Computed tomography showed the dilatation of left renal pelvis and a mass along with a left lower ureter. Retrograde pyelography showed the stenosis of left lower ureter. Urine cytologies from both voided and upper urinary tract showed class I. Ureteroscopy revealed the normal ureteral mucosa, suggesting extrinsic obstruction of the ureter. The operation was performed under the diagnosis of retropelvic tumor. The tumor could be easily resected from the left ureter. The pathological diagnosis was follicular lymphoma. There was no prolificative accumulation on Gallium scintigraphy after the operation. The tumor was considered to have originated from paraureteral tissue.