Department of Pathology, Hospital Álvaro Cunqueiro, Vigo, Spain.
Uropathology Research Group, Galicia Sur Health Research Institute (IIS Galicia Sur) SERGAS-UVIGO, Vigo, Spain.
Int J Surg Pathol. 2024 Jun;32(4):772-775. doi: 10.1177/10668969231188894. Epub 2023 Jul 31.
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.
黏液样假瘤是一种假瘤性纤维母细胞增生，已在肾周和肾窦脂肪组织中描述。其特征为存在黏液样基质，与脂肪细胞交织在一起，还有稀疏的梭形和星状细胞。我们报告了一例累及输尿管远端的黏液样假瘤，这拓宽了该病变在泌尿道周围可能定位的范围。它发生在一名 80 岁的患者中，该患者因偶然发现左输尿管远端壁增厚而接受了肾输尿管切除术，该影像学提示可能为输尿管肿瘤。他有两次尿脱落细胞学检查和一次输尿管镜活检，诊断为高级别尿路上皮癌，以及逆行输尿管镜输尿管活检，诊断为原位尿路上皮癌。这强调了由于影像学解释不当，加上术前细胞组织学恶性数据，黏液样假瘤可能被误诊为输尿管浸润性癌的问题。我们的标本中未见浸润性或乳头状肿瘤，弥漫性原位尿路上皮癌。这不能支持黏液样假瘤假设的阻塞性发病机制。
