case_images: PMC4850880_01
case_images: CT scans show multiple tumors in the right kidney (
  A and
  B). Gross examination displays a yellowish central tumor with solid-cystic areas corresponding to a clear cell renal cell carcinoma (
  C) and four peripheral whitish tumors and several intrarenal micronodules corresponding to biphasic squamoid alveolar renal cell carcinomas (
  C and
  D).
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case_images: PMC4850880_01_f1000research-5-9388-g0000.jpg
case_images: f1
case_images: CT scan revealed multiple tumors on his right kidney, four of them being located at the periphery ( Figure 1). Figure 1). Four tumors were subcapsular and showed a whitish homogeneous cut surface, measuring between 1 and 3 cm in diameter.
case_images: Panoramic view of both tumors, Biphasic squamoid alveolar renal cell carcinoma (BSARCC) (
  A and
  B) and conventional renal cell carcinoma (CCRCC) (
  C and
  D). BSARCC displayed some areas of type1 papillary renal cell carcinoma (
  A, right side) and presented the typical alveolar structures filled with large cells (
  A, left side and
  B). CCRCC showed solid and cystic areas composed of nests low-grade cells with clear cytoplasm (
  C and
  D).
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case_images: PMC4850880_01_f1000research-5-9388-g0001.jpg
case_images: f2
case_images: Histologically, the yellowish central tumor was a conventional organ-confined CCRCC grade 1 (ISUP 2013)  ( Figure 2). On low-power view, all the whitish peripheral tumors and the micronodules displayed a similar histology consisting in areas reminiscent to glomerular-like structures ( Figure 2 and Figure 3) alternating with others typical of type 1 PRCC.
case_images: Microscopic detail of the alveolar structures containing small groups and single large squamoid cells (
  A and
  B).
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case_images: PMC4850880_01_f1000research-5-9388-g0002.jpg
case_images: f3
case_images: On low-power view, all the whitish peripheral tumors and the micronodules displayed a similar histology consisting in areas reminiscent to glomerular-like structures ( Figure 2 and Figure 3) alternating with others typical of type 1 PRCC. The alveoli were filled with cell groups with large cytoplasm and squamoid appearance ( Figure 3).
case_images: Immunohistochemical study with 34betaE12 (
  A), RCC marker (
  B), CK7 (
  C), cyclin D1 (
  D), PAX-8 (
  E) and AMACR (
  F). Noteworthy, 34betaE12 and cyclin D1 selectively immunostain the central squamoid cell groups and, conversely, RCC marker does it only in peripheral alveolar cells. CK7, PAX-8 and AMACR immunostain both cell types.
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case_images: PMC4850880_01_f1000research-5-9388-g0003.jpg
case_images: f4