Eosinophilic Vacuolated Tumor of Kidney: Clinical Perspective of a New Pathologic Emerging Entity

Abstract

The eosinophilic vacuolated tumor (EVT) of the kidney is a newly identified and pathological emerging entity. In this case report, EVT diagnosed due to a partial nephrectomy performed for a suspicious kidney mass in a 47-year-old patient is presented. A review of the literature and this case indicates that EVT, also called high-grade oncocytoma, does not show clinically aggressive behavior. However, in case of clinical suspicion, tumors with this oncocytic morphology should be treated with nephron-sparing treatment methods, considering that they may be hybrid malignancies.

Update on Selected Oncocytic Renal Cell Tumors

“…1 To date, nearly 60 cases have been reported. 8,[19][20][21][22][23][24][25][26][27][28][29][30] EVTs occur slightly more frequently in women (M:F = 1:1.3), with a broad age range of 15-73 years old (mean age: 49 years old; median age: 50 years old). They typically occur sporadically; however, they also have been reported to be associated with TSC.…”

“…The mean tumor size is 3.5 cm (median: 3.1 cm; range: 1.3-11.5 cm). 8,[19][20][21][22][23][24][25][26][27][28][29][30] Microscopically, EVT typically shows a solid, nested, compact acinar, as well as focal tubular or tubulocystic architecture (Fig. 1a).…”

“…1d), and they are nearly always negative for RCC, vimentin, melanoma antigen, transcription factor E3, and transcription factor EB. 9,12,[19][20][21][22][23][24][25][26][27][28][29][30] Cytokeratin (CK) 7 and CK20 positivity are typically restricted to scattered tumor cells (CK7 in 22/54 or 40% of tumors, CK20 in 11/36 or 30% of tumors) (Table 2). The neoplastic cells are positive for paired box gene 8 (PAX8) and show retained expression of succinate dehydrogenase B (SDHB) and fumarate hydratase (FH).…”

“…9,12,20,24,25 The copy number alterations in EVTs include the loss of chromosome 1 and chromosome 19 as well as the loss of heterozygosity on 16p11.2-11.1 and 7q31.31. 9,11,20 The pathologic stage of all reported cases was pT1, 9,12,[19][20][21][22][23][24][25][26][27][28][29][30] except one case with pT2. 11 So far, all reported cases have exhibited an indolent behavior.…”

Case of the Month from San Raffaele Hospital, Milan, Italy: paraneoplastic presentation of small renal masses

“…In particular, new entities encompass ESC‐RCC. These include low‐grade oncocytic renal tumour (LOT), high‐grade oncocytic renal tumour (HOT), anaplastic lymphoma kinase rearrangement‐associated RCC (ALK‐RCC) and eosinophilic vacuolated tumour (EVT) [3].…”