Rare MDM2 amplification in a fat-predominant angiomyolipoma

Academic Article

Abstract

  • © 2020, Springer-Verlag GmbH Germany, part of Springer Nature. Angiomyolipomas (AMLs) are triphasic tumors (smooth muscle, vascular and adipocytic components) with myomelanocytic differentiation, arising most commonly in the kidneys, which can show predominant epithelioid morphology and fat-predominant or fat-poor variants. Fat-predominant AMLs can show areas of hypercellularity and lipoblast-like cells, and these features can mimic well-differentiated liposarcoma (WDLS). To date, only one documented metastatic epithelioid AML showed unequivocal MDM2 amplification by fluorescence in situ hybridization. We describe our findings in a series of 35 AMLs including epithelioid, fat-poor, and fat-predominant variants, following interrogation of the MDM2 locus by FISH and CISH assays. MDM2 amplification was detected in 1 fat-predominant AML. Our findings demonstrate that rare MDM2 amplifications can occur in AMLs. We favor that this finding likely represents a “molecular bystander” event since these tumors are mainly driven by aberrations in the TSC1/TSC2 genes. Nevertheless, the presence of MDM2 amplification in a fat-predominant AML could present a potential diagnostic pitfall, particularly when confronted with the differential diagnosis of fat-predominant AML and WDLS in limited material from the retroperitoneum.
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    Author List

  • Rodriguez Pena MDC; Gordetsky J; Greipp PT; Wei S; Martignoni G; Netto GJ; Harada S; Prieto Granada CN