Renal cell carcinoma

Renal cell carcinomas (RCC) are primary malignant adenocarcinomas derived from the renal tubular epithelium and are the most common malignant renal tumour. They usually occur in 50-70-year-old patients and macroscopic haematuria occurs in 60% of the cases. 

On imaging, they have a variety of radiographic appearances, from solid and relatively homogeneous to markedly heterogeneous with areas of necrosis, cystic change and haemorrhage.

Patients are typically 50-70 years of age at presentation 1-2, with a moderate male predilection of 2:1 2.

Renal cell carcinomas are thought to be the 8th most common adult malignancy, representing 2% of all cancers, and account for 80-90% of primary malignant adult renal neoplasms 4,7.

Presentation is classically described as the triad of:

  1. macroscopic haematuria: 60%
  2. flank pain: 40%
  3. palpable flank mass: 30-40%

This triad is however only found in 10-15% of patients 1,2, and increasingly the diagnosis is being made on CT for assessment of haematuria alone or as an incidental finding. The majority of cases are sporadic. In contemporary medicine, almost half of all identified renal cell carcinomas are found incidentally on imaging performed for other purposes.

Paraneoplastic syndromes

Around 25% of RCC patients will develop a paraneoplastic syndrome 19-21:

Risk factors

Renal cell carcinomas arise from tubular epithelium, and encompasses a number of distinct histological varieties, including 4-6:

Macroscopic appearance

Macroscopically, renal cell carcinomas are variable in appearance, ranging from solid and relatively homogeneous to markedly heterogeneous with areas of necrosis, cystic change and haemorrhage 4.

Low grade, smaller tumours typically have a pseudo capsule composed of compressed and ischaemic normal renal tissue. The presence of a pseudo capsule is only seen in renal cell carcinomas, renal adenomas and oncocytomas 8.

Renal cell carcinoma is one of the (more common) causes of cannonball metastases to the lung.

Grading
Histological nuclear grading

The most widely used and most predictive grading system for renal cell cancer is the "Fuhrman nuclear grade" which is on a scale of I-IV, where grade I carries the best prognosis and grade IV the worst.

Associations

In some instances RCCs are associated with 2:

Imaging is essential in accurately staging renal cell carcinomas (see RCC staging (TNM) and Robson staging) and in operative planning.

Ultrasound

Although ultrasound is very frequently requested to assess the renal tract, it is not as sensitive or specific as CT or MRI. Furthermore, it struggles to accurately locally stage the disease in many instances 4.

Renal cell carcinoma has a widely varying sonographic appearance. It may appear solid or partially cystic, and may be hyper, iso, or hypoechogenic to the surrounding renal parenchyma.22 The tumour pseudo capsule can sometimes be visualised with ultrasound as a hypoechoic halo. Although this is a relatively specific sign, it not particularly sensitive (~20%). Use of harmonic scanning has been reported to increase sensitivity to up to 85% 8.

Contrast-enhanced ultrasound 16 demonstrated the lesion to be heterogeneously hypervascular in the arterial phase with early washout in the delayed phase.

CT

CT is frequently used to both diagnose and stage renal cell carcinomas. On non-contrast CT the lesions appear of soft tissue attenuation. Larger lesions frequently have areas of necrosis. Approximately 30% demonstrate some calcification 7.

During the corticomedullary phase of enhancement, 25-70 seconds after administration of contrast, renal cell carcinomas demonstrate variable enhancement, usually less than the normal cortex. Small lesions may enhance a similar amount and be difficult to detect 7. In general small lesions enhance homogeneously, whereas larger lesions have irregular enhancement due to areas of necrosis. The clear cell subtype may show much stronger enhancement 5.

The corticomedullary phase is also best for assessing vascular anatomy, both for renal vein involvement, and for arterial variation if partial nephrectomy is being contemplated 7. Intraluminal growth into the venous circulation, in particular, the renal vein, occurs in 4-15% 12. The prognosis is significantly worse for those with IVC involvement compared to renal vein involvement alone, making identification on CT important 13.

The nephrogenic phase (80-180 seconds) is the most sensitive phase for detection of abnormal contrast enhancement.

Excretory phase is of less worth, but important in assessing the collecting system anatomy especially if the candidate is a potential candidate for a partial nephrectomy.

Follow-up imaging after treatment is typically done with CT, with dual-phase imaging of the abdomen advocated to maximise the detection of solid organ metastases 9. Renal cell carcinoma typically causes hypervascular metastases, best appreciated on arterial phase imaging of the upper abdomen.

MRI

MRI is not only excellent at imaging the kidneys and locally staging tumours, but is also able to suggest the likely histology, on the grounds of T2 differences.

  • T1: often heterogeneous due to necrosis, haemorrhage and solid components
  • T2: appearances depend on histology 6
    • clear cell RCC: hyperintense
    • papillary RCC: hypointense
  • T1 C+ (Gd): often shows prompt arterial enhancement

Tumour pseudo capsule, essentially only seen in low-grade renal cell carcinomas, renal adenomas and oncocytomas appears as a hypointense rim between the tumour and the adjacent normal renal parenchyma 8.

MRI is also useful for imaging renal vein and IVC tumour thrombus and the rostral extension (important in preoperative planning). The presence of enhancement in the thrombus is able to distinguish between bland and tumour thrombus 4.

The use of diffusion-weighted sequences has been explored in assisting with characterising indeterminate small renal lesions, which may be inflammatory or malignant in nature, both exhibit restricted diffusion, albeit the restriction is greater with abscess than tumour 10.

Treatment of renal cell carcinomas is usually with radical nephrectomy if feasible. However, in elderly patients or those with co-morbidities, and especially those with smaller tumours suggestive of papillary histology (see MRI findings above) then organ-sparing treatment can be entertained. This ranges from adrenal sparing nephrectomy to partial nephrectomy, performed both open or laparoscopically. Additionally, percutaneous radiofrequency or cryoablation (typically under CT guidance), which can be carried out with only local anaesthetic and sedation, has been introduced in selected cases 11.

Prognosis can be variable depending both on histological subtype and stage.

The papillary variant carries the best prognosis (5-year survival of 90%), followed by clear cell (conventional) RCC (5-year survival 70%), while collecting duct subtype carry the worst 6.

As far as the effects of tumour stage (see renal cell carcinoma staging) are concerned, there is a dramatic difference between stage I and IV tumours:

  • stage I: 90% 5-year survival
  • stage II: 50% 5-year survival
  • stage III: 30% 5-year survival
  • stage IV: 5% 5-year survival

The broad differential is essentially that of all renal masses, particularly other renal tumours, and most commonly includes:

Share article

Article Information

rID: 7534
System: Urogenital
Section: Pathology
Synonyms or Alternate Spellings:
  • Renal cell cancer
  • Renal cell carcinoma (RCC)
  • RCC
  • Hypernephroma
  • Renal cell carcinomas
  • Renal cancer
  • Kidney cancer
  • Grawitz tumour
  • Renal cell cancers

Support Radiopaedia and see fewer ads

Cases and Figures

  • Drag
    Renal cell carcin...
    Figure 1: gross pathology - renal cell carcinoma
    Drag here to reorder.
  • Drag
    RCC Coronal
    Case 1
    Drag here to reorder.
  • Drag
    There is a multi-...
    Figure 2: expansile tumour with renal vein invasion
    Drag here to reorder.
  • Drag
     Case 2
    Drag here to reorder.
  • Drag
    Figure 3: gross pathology - cystic RCC
    Drag here to reorder.
  • Drag
    Case 4
    Drag here to reorder.
  • Drag
    Macroscopic - Cir...
    Figure 4: gross pathology - papillary RCC
    Drag here to reorder.
  • Drag
    Case 5
    Drag here to reorder.
  • Drag
    Clear cell RCC - ...
    Figure 5: histology
    Drag here to reorder.
  • Drag
    Case 6
    Drag here to reorder.
  • Drag
    Rcc
    Case 7
    Drag here to reorder.
  • Drag
    Case 8
    Drag here to reorder.
  • Drag
    Case 9: multicystic RCC
    Drag here to reorder.
  • Drag
    Case 10: clear cell - with horseshoe kidney
    Drag here to reorder.
  • Drag
    RCC (papillary) :...
    Case 11: papillary type
    Drag here to reorder.
  • Drag
    Case 12: papillary
    Drag here to reorder.
  • Drag
    Case 13: with IVC invasion
    Drag here to reorder.
  • Drag
    Case 14: with renal vein invasion
    Drag here to reorder.
  • Drag
    Case 15: recurrent RCC
    Drag here to reorder.
  • Drag
    Case 16: solid hypovascular - papillary type I
    Drag here to reorder.
  • Drag
    Case 17: with para-aortic nodal recurrence
    Drag here to reorder.
  • Drag
    Case 18: with lung metastases
    Drag here to reorder.
  • Drag
    RCC metastasis
    Case 19: with hypervascular mesenteric secondaries
    Drag here to reorder.
  • Drag
    The mass shows av...
    Case 20
    Drag here to reorder.
  • Drag
    Case 21
    Drag here to reorder.
  • Drag
    Case 22
    Drag here to reorder.
  • Drag
    Case 23
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.