Myxoid Pseudotumor Changes Affecting the Distal Ureter Associated With Urothelial Carcinoma In Situ.

Abstract

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.

• Authors: José A Ortiz-Rey, Alejandra García-Baizán, Alejandro Bellas-Pereira, Araceli Barciela-Bastos, Carolina Gómez-de María, Marta Conde-Ferreirós
• Journal: International journal of surgical pathology (Int J Surg Pathol) Pg. 10668969231188894 (Jul 31 2023) ISSN: 1940-2465 [Electronic] United States
• PMID: 37525552 (Publication Type: Journal Article)