Renal cell carcinoma is the most common primary malignant tumor of the kidney. It originates from the proximal convoluted tubules within the cortex of the kidney.
It comprises 85% of all the malignancies of the kidneys in the adult. It is more common in males than females. It commonly occurs at an average age of 55 years.
- Flank pain
- Palpable flank mass
- Weight loss
- Paraneoplastic syndrome
- Renin cause hypertension
- Erythropoietin cause polycythemia
- Parathormone (PTH) cause hypercalcemia
- Gonadotropin cause gynecomastia
- ACTH cause Cushing syndrome
- Stauffer syndrome: It is nephrogenic hepatopathy in the absence of hepatic metastases.
Risk Factors Of The Renal Cell Carcinoma:
Renal cell carcinoma have increased incidence with
- Von Hippel-Lindau disease
- Long-term renal dialysis.
- Tobacco use
- Long term phenacetin use
- Family history
Radiographic Features Of The Renal Cell Carcinoma:
- Soft tissue mass on plain film can be seen if tumors are large.
- 10% of renal cell carcinoma show some calcification on plain film.
- Calcification is dense central and amorphous.
- After contrast administration mass is seen displacing adjacent calyces.
- The renal outline is distorted.
- Renal cell carcinoma shows similar enhancement to normal renal tissue on nephrogram.
- If the tumor has occluded the renal vein then there is an absence of contrast excretion.
- Tumors less than 3cm in diameter are not seen on IVU.
- Smaller tumors < 3cm appears as hyperechoic mass.
- Large tumors > 3cm appear as iso- or hypoechoic mass compared to normal renal tissue.
- Macroscopic calcific foci are present.
- The renal cell carcinoma show heterogeneity due to necrosis, hemorrhage and cystic degeneration.
- Smaller tumors < 3cm are well-defined, homogeneous and solid ( > 20HU)
- Larger tumors > 3cm are ill-defined, heterogeneous and shows areas of necrosis.
- Calcifications are present.
- Perinephric fat stranding is seen due to edema, vascular engorgement, and tumor invasion.
- Renal cell tumors are usually isodense or hypodense compared to normal renal tissue.
- They enhance variably but mostly enhance less than renal tissue.
- They show heterogeneous enhancement because of necrosis and cystic areas.
- Enhancing nodule is seen in perinephric space when it is involved.
- Low attenuation filling defect in corticomedullary phase is the most specific sign for renal vein thrombus.
- Other features of renal vein thrombus are
- Abrupt change in caliber of vein
- Presence of collateral veins
- Heterogeneous enhancement of malignant thrombus
- Enlarged lymph nodes are present.
- On MRI renal cell carcinoma appears of intermediate signal intensity on T1WI.
- They appear high signal on STIR
- They show intermediate to high signal intensity on T2WI.
- Imaging at 2-5 mins post contrast is critical for detection of small renal mass as thy show less enhancement than in the normal tissue.
- On angiography, renal cell carcinoma is typically hypervascular.
- Enlarged tortuous feeding vessels.
- Neovascularity with the formation of small aneurysms.
- Poorly defined tumor margins.
- AV shunting.
- Mets of the renal cell carcinoma spread to bone, brain, liver, lung, lymph nodes and to the contralateral kidney.
- These Mets are hypervascular.
- They are expansile and osteolytic.
- The patient can also present with signs and symptoms of metastases such as a cough, hemoptysis and bone pain etc.
- The 5-year survival for stage I and II is 50%.
- For stage III it is 35%.
- And for stage IV it is 15%.
Staging Of The Renal Cell Carcinoma:
- Once the diagnosis has been made, it is necessary to stage them.
- Two staging systems are available i.e Robson classification & the TNM staging system.
- MRI is the best choice of modality to assess stage.
Robson classification of renal cell carcinoma
TNM staging of renal cell carcinoma
- Radical nephrectomy (entire contents of gerota’s fascia is removed).
- Nephron-sparing surgery also called partial nephrectomy.
- Radiotherapy is used for palliation.