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
