PMC3629044_01
Computed tomography and magnetic resonance imaging showing a large solid mass located in the middle and lower pole of the left kidney with hydronephrectasis.
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Computed tomography (CT) and magnetic resonance (MR) scan revealed an expansile, solid mass measuring ~10 cm in the middle lower pole of the left kidney (Fig. 1).
The cut surfaces of the tumor were yellowish gray and solid with an ill-circumscribed border.
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Macroscopically, the specimen was ill-circumscribed and measured 10 cm at its greatest dimension, and hydronephrectasia could be seen in the left kidney due to the occupation of the tumor; the cut surfaces were yellowish gray and solid (Fig. 2).
The composite tumor showing metanephric adenoma (MA; right side) along with Wilms' tumor (WT; left side) separated by tiny fibrous stroma (hematoxylin and eosin; magnification, x100).
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MA and WT that were separated by a band of fibrous stroma (Fig. 3). MA showed a pushing border with no capsule and an ordered array of small, tightly packed acini and tubules separated by acellular stroma (Fig. 4), but no papillary structure.
The metanephric adenoma (MA) area showed ordered array of small, tightly packed acini and tubules. Tumor cells are small and uniform with round to oval nuclei and scant cytoplasm (hematoxylin and eosin; magnification, x400).
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MA and WT that were separated by a band of fibrous stroma (Fig. 3). MA showed a pushing border with no capsule and an ordered array of small, tightly packed acini and tubules separated by acellular stroma (Fig. 4), but no papillary structure.
Wilms' tumor (WT) area showed predominantly epithelial components which are in the form of poorly formed tubules to well-developed tubular structures. The typical blastemal and stromal components were rare (hematoxylin and eosin; magnification, x400).
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Tumor cells showing CD57 expression in the metanephric adenoma area (right side) as compared with negativity in the Wilms' tumor area (left side) (immunohistochemistry; magnification, x100).
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In the MA area, tumor cells showed positive diffuse staining for CD57 (Fig. 6), WT-1 (Fig. 7), focal staining for vimentin, pan CK, CK7 and CK8/18, but negative staining for epithelial membrane antigen (EMA).
Tumor cells showing WT-1 expression in the Wilms' tumor area (left side) as compared with negativity in the metanephric adenoma area (right side) (immunohistochemistry, magnification, x100).
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In the WT area, tumor cells stained diffusely for WT-1 (Fig. 7), CK8/18, focally for vimentin, pan CK, EMA, CD57 (Fig. 6), but were negative for CK7.
The Ki67 labeling index was significantly higher in the Wilms' tumor area (left side) as compared with that of the metanephric adenoma area (right side) (immunohistochemistry; magnification, x100).
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The Ki67 labeling index (Fig. 8) was 2%. In the WT area, tumor cells stained diffusely for WT-1 (Fig. 7), CK8/18, focally for vimentin, pan CK, EMA, CD57 (Fig. 6), but were negative for CK7. The Ki67 labeling index (Fig. 8) was 50-60%.