Classification of Renal tumors and its morphology

CLASSIFICATION OF RENAL TUMORS

WHO classification of Renal tumors

• Renal cell tumors

  • Benign

    • Papillary adenoma

    • Oncocytoma

  • Malignant

    • Renal cell carcinoma

      • Clear cell carcinoma

      • Papillary renal cell carcinoma

      • Chromophobe renal cell carcinoma

      • Collecting duct carcinoma

      • Renal medullary carcinoma

      • Mucinous tubular and spindle cell carcinoma

      • Tubulocystic renal cell carcinoma

      • Aquired cystic disease – associated renal cell carcinoma

      • Clear cell papillary renal cell carcinoma

      • Renal cell carcinoma unclassified

• Metanephric tumors

  • Metanephric adenoma

  • Metanephric adenofibroma

  • Metanephric stromal tumor

• Nephroblastic and cystic tumros occuring mainly in children

  • Nephrogenic rests

  • Nephroblastoma

  • Cystic partially differentiated nephroblastoma

  • Paediatric cystic nephroma

• Mesenchymal tumors

  • Mesenchymal tumors occuring in children

    • Clear cell sarcoma

    • Rhabdoid tumor

    • Congenital mesoblastic nephrom

    • Ossifying renal tumor of infancy

  • Mesenchymal tumor occuring in adults

    • Juxtaglomerular cell tumor

    • Leiomyoma

    • Haemangioma

    • Hemangioblastoma

    • Angiomyolipoma

    • Lymphangioma

    • Schwannoma

    • Solitary fibrous tumor

    • Leiomyosarcoma

    • Angiosarcoma

    • Rhabdomyosarcoma

    • Osteosarcoma

    • Synovial sarcoma

    • Ewing sarcoma

• MIxed epithelial and stromal tumors

• Neuroendocrine tumor

• Miscellaneous tumors

  • Renal Hematopoietic neoplasms

  • Germ cell tumors

• Metastatic tumors

 

MORPHOLOGY OF RENAL CELL CARCINOMA

• RCC affects mostly poles of the kidney

• Clear cell RCC

  • Occurs as solitary unilateral circumscribed tumor which is bright yellow to gray white in colour.

  • Yellow colour is due to lipid accumulation in tumor cells.

  • Cut section – variegated with hemorrhagic & necrotic areas.

  • Microscopy-

    • Tumor cells are arranged in trabecular or tubular or solid or cystic pattern.

    • Tumor cells are polygonal or rounded having abundant clear or granular cytoplasm containing glycogen and lipids

    • Delicate vascular branching may be present

    • Tumor may invade pelvic calyces & may extend into ureter.

    • Characteristic feature in RCC is, it invades renal vein, interior vena cave and grows as solid cords of cells and may also extend into the right  side of the heart

• Papillary carcinoma

  • Can be multifocal and bilateral

  • Grossly they are large cystic & hemorrhagic

  • Microscopic:

    • Tumor cells are cuboidal to low columnar cells lining the papillae having fibrovascular core with foamy macrophages

    • Psammoma bodies may be present

    • Highly vascularised scant stroma is present.

• Chromophobe RCC

  • Tumor cells have pale eosinophilic cytoplasm with perinuclear halo

  • Cells are arranged in solid sheets with perivascular arrangement of tumor cells

• Collecting duct carcinoma

  • Tumor has irregular channels lined by highly atypical epithelium with hobnail pattern.

Reference 

• Charles E. Alpers. The Kidney. In: Vinay Kumar, Abul K. Abbas, Nelson Fausto, Jon C. Aster. Robbins And Cotran Pathologic Basis of Disease. Eighth edition, 2011;Chapter 20: 905-970