CT/MRI imaging and immunohistochemical analyses of eosinophilic vacuolar tumor of the kidney: case reports of four patients.

purposeTo identify the imaging features, clinicopathological characteristics and imaging-pathology correlation, of eosinophilic vacuolar tumor of the kidney (EVT).

methodsPre-operative imaging (2 CT and 2 MRI, both including dynamic contrast imaging) and pathological data were retrospectively analyzed for 4 EVT patients (2 male, 2 female) between January 2022-December 2024. Follow-up was performed for 2-11 months post-partial nephrectomy. All the findings were compared to previous cases in the literature.

resultsEVT patients had an average age of 43 years, and average maximum tumor diameter of 3.8 cm (range 2.8-5 cm). In 2 cases, contrast-enhanced CT showed patterns associated with clear cell renal cell carcinoma (ccRCC) and lipid-poor angiomyolipoma, respectively, and in 2 other cases MRI scans showed masses with isointense or hypointense T1 and hyperintense T2 (relative to the renal parenchyma), with contrast enhancement showing abundant vessels similar to those observed for ccRCC. Histologically, EVT cells were arranged in nests and sheets, with abundant highly vacuolar eosinophilic cytoplasm, prominent nucleoli, and rare mitotic figures. IHC found that they were positive for CD117, PAX8, e-cadherin, among others, and negative for cytokeratin 7, carbonic anhydrase IX, and vimentin. Ki67 proliferation index was 5%, and patients were tumor-free at a mean follow-up of 7 months.

conclusionEVT is a rare renal tumor entity with characteristic imaging features, though its imaging presentation may vary depending on the underlying pathology. Accurate identification of EVT will contribute to improving the classification and diagnosis of renal tumors.