CASE OF THE WEEK
Editor: Mahmut Akgul (akgulm@amc.edu)
2022-17/April 25
Contributors: Caroline Passos Cardoso, Daniel Athanazio
A man in his early 50s under went a total nephrectomy due to a 4.5cm solid tumor.
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Quiz
What is the correct diagnosis?
a) Eosinophilic vacuolated tumor / High-grade oncocytic tumor
b) Oncocytoma
c) Eosinophilic, solid and cyst renal cell carcinoma
d) Chromophobe renal cell carcinoma
e) Epithelioid angiomyolipoma
1. c
1. a
A subset of renal cell tumors is characterized by cells with oncocytic and vacuolated cytoplasm, high-grade nuclear/nucleolar features, a particular immunophenotype (cytokeratin 7 negative or restrict to single cells or small clusters, cKIT/CD117 positive, cytokeratin 20 negative) and common association with some genetic alterations (somatic TSC2 or MTOR mutations)(1). Recently, the Genitourinary Pathology Society (GUPS) recommended the use of “Eosinophilic vacuolated tumor (EVT)” as the preferred name of this emerging entity. Similar cases have been recently reported and designated in literature as EVT (2,3), high-grade oncocytic tumor (4) and sporadic RCC with eosinophilic and vacuolated cytoplasm (5).
Proper identification of these tumors is important to separate them from the classification as unclassified eosinophilic renal cell carcinoma. Despite its high-grade features, these tumors are believed to behave as indolent neoplasms (as far as the available follow up indicates).
In our case, immunohistochemistry showed focal cytokeratin 7 expression (restricted to strong expression in single cells, mirroring what is expected in oncocytomas). The tumor was positive for PAX8 and showed diffuse cKIT/CD117 membrane staining. Tumor cells did not express carbonic anhydrase IX, TFE3 and cytokeratin 20 –the latter being important to help in the differential diagnosis of eosinophilic, solid and cyst renal cell carcinoma (ESC-RCC). In this case, there was a prominent component of nested growth within a loose stroma –a morphology very reminiscent of what is seen in oncocytoma(4).
In the description of 14 cases diagnosed as high-grade oncocytic tumors, 13 showed this pattern. Diffuse presence of high-grade nuclei with prominent nucleoli are an important feature to distinguish these tumors from oncocytoma, hybrid oncocytic/chromophobe tumor and oncocytic renal neoplasm of low malignant potential, not further classified –using the terminology also recently recommended by GUPS (4,6). Entrapped non-neoplastic renal tubules was also easily detected in tumor periphery of our case, and this feature was observed in all cases of the same series of high-grade oncocytic tumors(4). Psammomatous laminated calcifications were frequent in our case and was described in at least one reported case diagnosed as EVT (2).
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5. Chen YB, Mirsadraei L, Jayakumaran G, Al-Ahmadie HA, Fine SW, Gopalan A, Sirintrapun SJ, Tickoo SK, Reuter VE. Somatic Mutations of TSC2 or MTOR Characterize a Morphologically Distinct Subset of Sporadic Renal Cell Carcinoma With Eosinophilic and Vacuolated Cytoplasm. Am J Surg Pathol. 2019 Jan;43(1):121-131.
6.Trpkov K, Hes O, Williamson SR, Adeniran AJ, Agaimy A, Alaghehbandan R, Amin MB, Argani P, Chen YB, Cheng L, Epstein JI, Cheville JC, Comperat E, da Cunha IW, Gordetsky JB, Gupta S, He H, Hirsch MS, Humphrey PA, Kapur P, Kojima F, Lopez JI, Maclean F, Magi-Galluzzi C, McKenney JK, Mehra R, Menon S, Netto GJ, Przybycin CG, Rao P, Rao Q, Reuter VE, Saleeb RM, Shah RB, Smith SC, Tickoo S, Tretiakova MS, True L, Verkarre V, Wobker SE, Zhou M, Gill AJ. New developments in existing WHO entities and evolving molecular concepts: The Genitourinary Pathology Society (GUPS) update on renal neoplasia. Mod Pathol. 2021 Jul;34(7):1392-1424. doi: 10.1038/s41379-021-00779-w
Caroline Passos Cardoso
Federal University of Bahia / Hospital Universitário Professor Edgard Santos,
Salvador, Bahia, Brazil
Daniel Athanazio
Imagepat, Laboratory of Pathology, Federal University of Bahia / Hospital Universitário Professor Edgard Santos,
Salvador, Bahia, Brazil
Kidney
Kidney; Kidney Neoplasms; eosinophilic vacuolated tumor