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Renal Cell Carcinoma – Malignant Renal Tumor

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.

Clinical Findings:

  • Hematuria
  • 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:

IVU:

  • 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.
IVU: Large left sided tumor distorting adjacent calyces
IVU: Large left sided tumor distorting adjacent calyces

Ultrasound:

  • 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.
Ultrasound: IVC showing thrombus
Ultrasound: IVC showing thrombus
Ultrasound: Renal cell carcinoma replacing normal tissue
Ultrasound: Renal cell carcinoma replacing normal tissue

NECT:

  • 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.

CECT:

  • 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.
CT: Large renal cell carcinoma with vascular involvement
CT: Large renal cell carcinoma with vascular involvement
  • 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
CT: RCC with contralateral renal vein involvement
CT: RCC with contralateral renal vein involvement
  • Enlarged lymph nodes are present.

MRI:

  • 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.

Angiography:

  • 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.

Metastases:

  • 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.

Prognosis:

  • 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.
CT: Stage I and II renal cell carcinoma
CT: Stage I and II renal cell carcinoma

Robson classification of renal cell carcinoma

Staging of renal cell carcinoma-Robson classification

TNM staging of renal cell carcinoma

TNM staging of renal cell carcinoma

 

Treatment:

  • Radical nephrectomy (entire contents of gerota’s fascia is removed).
  • Nephron-sparing surgery also called partial nephrectomy.
  • Chemotherapy
  • Radiotherapy is used for palliation.

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