p53 aberration and TFE3 gene amplification may be predictors of adverse prognosis in epithelioid angiomyolipoma of the kidney

BACKGROUND: Although epithelioid angiomyolipoma of the kidney has been studied by several groups, the reported prevalence of malignant behavior remains uncertain and there are not yet definitive predictive biomarkers. We evaluated the behavior of renal epithelioid angiomyolipoma in a consecutive series in a single institution and investigated the prognostic value of aberrant p53 expression and TFE3 gene abnormality. METHODS: We retrospectively reviewed 14 epithelioid angiomyolipomas, most with pure or close to pure epithelioid components, comprising 12 consecutive cases who had attended our institution and two consultation cases. Fluorescence in situ hybridization with TFE3 break-apart probe was performed on 14 cases. The 14 cases were also labeled for p53 and TFE3 by immunohistochemistry. All cases were followed up. RESULTS: Three of the epithelioid angiomyolipomas were strongly positive for TFE3 and two had a mutant expression of p53. Although no TFE3 gene rearrangement was found, the two tumors with strong TFE3 expression showed TFE3 gene amplification. Follow-up details were available for seven of the 12 consecutive cases: two of them had developed metastases and died (29%), their mean overall survival was 41 months, and both had mutant p53 expression. The two consultation cases with TFE3 gene amplification developed recurrence/metastasis within 1 year after surgery. CONCLUSIONS: Our series study from a single institution presented the prevalence of malignant behavior in pure epithelioid angiomyolipomas, although the small number of cases with follow-up data greatly reduced the accuracy. p53 may be a prognostic marker for epithelioid angiomyolipoma. Cases with TFE3 gene amplification had poor prognoses.