Home Education AUAUniversity Education Products & Resources Pathology for Urologists Kidney Mesenchymal and Other Tumors Secondary Tumors

Secondary Tumors

Image A

Image B


  • Involvement of the kidney is commonly part of a disseminated disease.
  • More multifocal and bilateral, but may present as solitary tumor mimicking primary tumor (image A) & (image B).
  • Lung carcinomas are the most frequent source of metastatic carcinoma.
  • Other common culprits: contralateral kidney, breast and GI tract.
  • Morphology, most common is adenocarcinoma (30%) (image C) followed by squamous cell carcinoma and small cell carcinoma.

Image C

Image D

Direct extension

  • Retroperitoneal sarcomas such as liposarcoma may involve the kidney and simulate a primary renal tumor.
  • Dedifferentiated areas may invade into the kidney as a more solid mass than the retroperitoneal well-differentiated lipomatous tumor.
    • The dedifferentiated liposarcoma mass can be mistaken as a renal tumor and the well-differentiated area may look like perinephric fat (image D).
  • High grade dedifferentiated liposarcoma are composed of spindle cells and may resemble sarcomatoid RCC.
    • Liposarcoma is MDM2+ and CDK4+ and sarcomatoid RCC is keratin+.