PMC3189466_01
X-ray of the pelvis (anterior-posterior) showing pathological fracture of the left femur neck (arrow).
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The patient was placed on nonweight-bearing status of the left hip after a fall. 3 months later he suffered a pathological fracture to the left femur neck (Figure 1).
PMC3189466_02
MRI and CT scan (inset (a) without IV contrast and (b) with IV contrast) of the abdomen and pelvis showing a large heterogeneously enhancing (inset (b)) exophytic left renal mass measuring 11.6 x 10.7 cm with multiple small calcifications (arrow inset (a)).
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fig2
The findings could be confirmed by MRI (Figure 2).
Whole body bone scan performed after left hip replacement showing mild salt-and-pepper appearance to the skull, sternum, and posterior ribs. The axial skeleton and the posterior left hemipelvis showed increased radionuclide activity suggestive of metastatic disease to these regions.
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There was also increased radionuclide activity at the posterior left hemipelvis, suggestive of metastatic disease to the axial skeleton and the lower appendicular skeleton (Figure 3).
H&E stainings ((a) 200x and (b) 400x magnification) of the tumor showing a mixture of spindle cell (predominant) and epithelioid cells with abundant amphophilic, clear, and focally granular pink cytoplasm. Epithelioid cells often line spaces, spindle cells form fascicles.
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Necrosis is not present (Figure 4).
Radical nephrectomy specimen demonstrating an intact kidney mass without perinephric fat measuring 18 x 12 x 7 cm and weight of 920 g. The tumor appears as solid, tan-pink, and well-circumscribed mass grossly confined by the renal capsule. Of note is the extensive number of dilated blood vessels and lymphatics.
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The uninvolved renal parenchyma was unremarkable (Figure 5). 
Immunostaining demonstrating strong nuclear positivity for TFE3 protein with only minimal background staining.
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PAS with and without diastase and colloidal iron stains was equivocal (Figure 6). TFE-3 was present (Figure 6).