PMC5972752_01
a, b: Precontrast computed tomography images showed a heterogeneous density mass with spot calcification. c: The mass showed moderate heterogeneous enhancement on corticomedullary phase with necrosis and many tumor vessels. d: The tumor showed continued enhancement on the nephrographic phase and (f) slight washout on the delayed phase. e: The filling defect in the left renal vein and enlarged retroperitoneal lymph nodes are shown.
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Figure1
Unenhanced computed tomography (CT) scans showed an ill-defined, irregular, slightly hyperdense mass (with size 11.9 x 10.0 x 10.1 cm) relative to renal parenchyma in the left kidney with corticomedullary involvement (Figure 1a). The mass had heterogeneous density with hypodense components in the center and spot calcifications at its low part (Figure 1b). The mass showed heterogeneous, moderate enhancement during the corticomedullary phase with necrosis in the center and many tumor vessels, continued enhancement during the nephrographic phase, and slight washout during the delayed phase (Figure 1c, d, f). The tumor was also found in the left renal vein (Figure 1e) and there were many enlarged retroperitoneal lymph nodes with a short-axis diameter of least 10 mm (Figure 1e).
a, b: Unenhanced computed tomography images showed recrudescence and abdomen metastases. c, d: Multiple lung metastases are shown.
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Figure3
Tumor cells were cytologically malignant and exhibited marked pleomorphism as well as atypical mitotic figures (Figure 2a). TFE3 (Figure 2b, c, d). Thus, the pathological diagnosis was EAML with malignant tendency. In the present case, fluorescence in situ hybridization (FISH) suggested X chromosome polyploidy resulting in TFE3 gene amplification without TFE3 gene fusion (Figure 2e). 
a - e: Hematoxylin and eosin staining and immunohistochemical staining (magnification x 400). a: Marked atypical large cells with abundant eosinophilic cytoplasm and atypical mitotic figures are shown. b, c, d: Tumor cells were focally expressed HMB-45 and positive for Melan-A and TFE3. e: Fluorescence in situ hybridization analysis (magnification x 1,000): TFE3 centromere is labeled as green fluorescence and TFE3 telomere is labeled as red fluorescence. There were many red and green fusion signals in the cell nucleus and no separation signal was found, suggesting X chromosome polyploidy resulting in TFE3 gene amplification.
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Figure2
Four months after surgery, an unenhanced CT scan showed recrudescence as well as multiple abdomen and lung metastases (Figure 3a, b, c, d, e).