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Myxoid pseudotumor is a pseudoneoplastic fibroblastic proliferation that has been described in the perinephric and renal sinus fat tissue. It is characterized by the presence of a myxoid matrix, intermingled with the adipocytes, and a hypocellular population of spindle-shaped and stellate cells. We report a myxoid pseudotumor involving the distal ureter, which broadens the spectrum of possible localizations of this lesion around the urinary tract. It occurred in an 80-year-old patient who underwent a nephroureterectomy indicated after an incidental radiological finding of a thickening of the distal left ureter wall which suggested a ureteral neoplasm. He had two voided urine and one ureteroscopic sample cytologies diagnosed as high-grade urothelial carcinoma, as well as a retrograde ureteroscopy ureteral biopsy which was diagnosed as urothelial carcinoma in situ. This emphasizes the problem of the possible misdiagnosis of myxoid pseudotumor as a ureteral infiltrative carcinoma due to the radiological findings being badly interpreted, compounded by the preoperative cytohistologic data on malignancy. A diffuse urothelial carcinoma in situ was seen in our specimen without infiltrative or papillary tumors. This would not support an obstructive pathogenetic mechanism as has been hypothesized for myxoid pseudotumor., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

We describe a case of congenital giant megaureter in a 16-year-old female. She presented with a 5-day history of abdominal distention, right flank pain and tenderness. Right pyelonephritis was suspected. Computerized tomography showed a large cystic abdominal mass with no appreciably functioning left kidney causing secondary compression of the contralateral right ureter. A left upper nephroureterectomy was performed, draining over 3.5 L of fluid. Our experience suggests that congenital giant megaureter should be considered in the differential for pediatric patients presenting with a cystic abdominal mass., (Copyright © 2021 Elsevier Inc. All rights reserved.)