pathology
Last reviewed 03/2023
Renal cell adenocarcinoma arises from the epithelium of the proximal convoluted tubule. Characteristically, the tumour cells are large and polygonal with clear cytoplasm due to the accumulation of glycogen and lipid; they are known as clear cell carcinomas. In some variants, the cells are granular and stain more intensely.
Tumours less than 2 cm in diameter are regarded as benign by some pathologists. These rarely show evidence of local invasion or metastatic spread. They typically show a characteristic yellow colour when cut; occasionally they show calcification which allows easier radiographic identification.
Larger tumours may extend to the perinephretic tissue. Invasion of the renal vein occurs quite readily. The tumour may grow as a long cord along the lumen of the inferior vena cava.
Common sites of metastasis are:
- lungs - "cannon ball metastases"
- liver
- bone, especially the spine
- para-aortic lymph nodes
Less common sites include:
- contralateral kidney - in 5%
- adrenals
- skin
- brain