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Clear Cell Papillary Renal Cell Carcinoma

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  • RCC with mixed low-grade papillary and clear cell morphologies.
  • In contrast to clear cell RCC, lacks 3p- or VHL gene mutations.
  • In contrast to papillary RCC, lacks +7 or -Y.
  • Uncommon, initially described in end-stage renal disease kidneys, but can also be seen in sporadic setting.
  • Gross: solid or with prominent cystic component, most are organ-confined small tumors (mean 2.5 cm).

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  • Histology:
    • Characterized by clear cell cytology in papillary, tubular or acinar architectures (image A), (image B), (image C), & (image D).
    • Must have low-grade nuclei (Fuhrman grade 2 or lower).
    • Nuclei are in linear arrangement.
    • Immunohistochemistry: diffusely CK7+ and AMACR+ like papillary RCC; diffusely CAIX+ like clear cell RCC.
    • Good prognosis; most reported tumors are low stage (pT1).
    • Main DDX: (Other tumors with mixed clear cell and papillary architecture)
      • TFE3 carcinomas: Usually in children or young adults, high-grade cytology and TFE3+.
      • Tumors with mixed clear cell and papillary tumor with high-grade nuclei lacking linear growth and TFE3-, considered under unclassified RCC.