Renal cell carcinoma
Updates to Article Attributes
Renal cell carcinomas (RCC) are malignant tumours derived from the renal epithelium. It is the most common malignant renal tumour, with a variety of radiographic appearances.
Epidemiology
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
Clinical presentation
Presentation is classically described as the triad of:
- macroscopic hematuria: 60%
- flank pain: 40%
- 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. There majority of cases are sporadic.
Paraneoplastic syndomes
- polycythaemia: from erythropoetin secretion
- hypercalcaemia:
- Stauffer syndrome: hepatic dysfunction not related to metastases
Associations and risk factors
In some instances RCCs are associated with: 2
- von Hippel-Lindau syndrome: greater tendency for bilateral RCC as well as presentation at a younger age
- Xp11.2 translocation
- familial clear cell cancer
- tuberous sclerosis
- hereditary renal cell cancer syndromes
Risk factors include :
- cigarette smoking 2
- dialysis-related cystic disease 2
- obesity
- treatment with cyclophosphamide (chemotherapy agent) 14
Pathology
Renal cell carcinomas arise from tubular epithelium, and encompasses a number of distinct histological varieties, including: 4-6
-
clear cell (conventional): 70-80%
- large uniform cells with clear cytoplasm (thus the name and T2 appearance (see below)
- highly vascular
- clear cell multilocular
- papillary: 15-20%
- type I - sporadic, generally good prognosis 4
- type II - inherited, bilateral and multi focal
- chromophobe: 5%
- similar histologically to renal oncocytomas 4
- best prognosis 5
- collecting duct (Bellini duct): < 1%
- often younger patients
- worst prognosis 5
-
renal medullary carcinoma : rare
- seen primarily in patients with sickle cell disease or sickle cell trait 4
Macroscopically renal cell carcinomas are variable in appearance, ranging form solid and relatively homogeneous to markedly heterogeneous with areas of necrosis, cystic change and haemorrhage. 4
Low grade, smaller tumours typically have a pseudocapsule composed of compressed and ischaemic normal renal tissue. The presence of a pseudocapsule is only seen in renal cell carcinomas, renal adenomas and oncocytomas 8.
Radiographic features
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.
The tumour pseudocapsule can sometimes be visualised with ultrasound as a hypoechoic halo. Although this is a relatively specific sign, it is only demonstrable in a minority of ultrasounds (~20%). Use of sonographic contrast and harmonic scanning has been reported to increase sensitivity to up to 85% 8.
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 (25-70 seconds) of enhancement following 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 sub type 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 signicantly 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.
Follow up imaging following treatment is typically with CT, with dual phase imaging of the abdomen advocated to maximize the detection of solid organ metastases.9
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 - hyper intense
- papillary RCC - hypo intense
- T1 C+ (Gd) - often shows prompt arterial enhancement
Tumour pseudocapsule, 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 at imaging renal vein and IVC tumour thrombus and the rostral extension (important in preoperative planning). 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 and prognosis
Typically renal cell carcinomas feasible a radical nephrectomy is performed, 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 ablation, 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 sub type 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
Differential diagnosis
The broad differential is essentially that of all renal masses, particularly other renal tumours, and most commonly includes:
- renal tumours
- renal adenoma : should be considered small, early renal cell carcinomas
- renal oncocytoma : particularly for chromophobe type
-
angiomyolipoma (AML)
- usually has a large component of fat
- 4-5% have little or not fat however 6
- renal metastasis
- renal lymphoma
- solitary fibrous tumour of the kidney : rare
-
renal pseudotumours
- haemorrhagic or complex renal cyst : see Bosniak classification
- renal abscess / pyelonephritis / lobar nephronia
- renal infarct
- hypertrophied column of Bertin
- direct extension of neighbouring tumours
- +<li>treatment with cyclophosphamide (chemotherapy agent) <sup>14</sup>
- +</li>
-<li>haemorrhagic or complex renal cyst : see <a href="/articles/bosniak_renal_cyst_classification">Bosniak classification</a>- +<li>haemorrhagic or complex renal cyst : see <a href="/articles/bosniak-renal-cyst-classification">Bosniak classification</a>
References changed:
- 14. Travis L, Curtis R, Glimelius B et al. Bladder and Kidney Cancer Following Cyclophosphamide Therapy for Non-Hodgkin's Lymphoma. J Natl Cancer Inst. 1995;87(7):524-30. <a href="https://doi.org/10.1093/jnci/87.7.524">doi:10.1093/jnci/87.7.524</a>
Image 2 CT (renal cortical phase) ( update )
Image 5 Pathology (Gross pathology) ( update )
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