Urology - Renal tumors Flashcards
Name some benign renal tumours? What is angiomyolipoma associated with?
All benign renal tumours are epithelial:
1) Adenoma - this tumour is often small and asymptomatic, it is derived from renal tubules. It may be a precursor lesion to renal cell carcinoma
2) Angiomyolipoma - this is a hamartoma consisting of fat, smooth muscle and blood vessels. It is often associated with tuberous sclerosis syndrome and large masses have a risk of sponataneous haemorrhage
3) Oncocytoma - these are composed of large eosinophilic cells. Grossly they have a mahogany brown colour due to mitochondrial lipochrome pigment
What is renal cell carcinoma?
This is the most common renal malignancy. It is a malignant lesion (adenocarcinoma) of the kidney arising from the proximal renal tubule epithelium. It is also called a hypernephroma or Grawitz’ tumour.
What is the epidemiology of RCC?
RCC is more common in males cf. females (1.6:1).
It is uncommon before the age of 40 and has a peak incidence between 50-70.
It accounts for 2-3% of all adult tumours, but 90% of all renal tumours.
What predisposing factors are important in the aetiology of RCC?
1) Diet: high intake of fat, oil and milk
2) Toxic agents: lead, cadmium, asbestos and large quantities of phenacetin containing analgesics
3) Cigarette smoking: doubles the risk of RCC!
4) Hypertension and obesity, especially in women
5) Genetic factors: HLA-DR8, oncogene on chromosome 3
6) Other diseases: VHL, hereditary papillary renal carcinoma, adult polycystic disease
What are the important histological variants of RCC?
The carcinoma originates in the renal tubules. Most often, it arises in one of the renal poles, frequently the upper pole.
It comes in several variants:
1) Clear cell RCC (75%) - it is grossly bright orange- yellow and microscopically demonstrates “clear cells” containing lipids and glycogen. Grading is based on predominance of nucleoli
2) Chromophilic (15%)
3) Chromophobic (5%) - eosinophilic granular cells with prominent cell borders. It closely mimics oncocytoma
4) Collecting duct (very aggressive)
How does RCC spread and where does it tend to metastasise to?
Spread is via:
- direct spread into renal vein and perirenal tissue
- lymphatic to para-aortic and hilar nodes
- haematogenous spread to lungs (large, cannon ball metastases), bones and to contralateral kidney
Common sites of metastasis are bones, kidney, brain, liver and lungs.
How is RCC staged?
RCC is staged using the TNM system. Increasing stage associated with worse prognosis (5 year survival).
Stage I = T1/N0/M0 - tumour is confined within renal capsule; 95%
Stage II = T2/N0/M0 - tumour confined by Gerota’s fascia,; 85%
Stage III = T1-T3/ N0-1/M0 - tumour to renal vein or IVC nodes or through Gerota’s fascia
Stage IV = distant metastasis or invasion of adjacent organs; 0-20%
What are the clinical features of RCC?
The classic triad of RCC is loin pain, haematuria and a palpable flank mass is rare now. The majority of patients are detected incidentally on abdominal imaging to investigate unrelated symptoms.
A full medical history should enquire about fatigue, weight loss, night sweats and symptoms from paraneoplastic syndromes.
Abdominal examination may ellicit a palpable mass and cervical lymphadenopathy. An acute left varicocele secondary to obstruction of the left renal vein may also be present. Lower limb oedema and caput medusa are present in advanced disease.
What paraneoplastic syndromes are associated with RCC?
1) Hypertension - ectopic renin secretion
2) Hypercalcaemia - ectopic PTH secretion
3) Anaemia - haematuria, chronic disease
4) Polycythaemia (causes visual disturbance, headcahes etc) - ectopic EPO secretion
5) Stauffer’s syndrome (= abnormal liver function tests, WBC, fever and areas of hepatic necrosis) - unknown, resolves in most patients with nephrectomy
What investigations are required in suspected RCC? What is the Bosniak classification?
Bloods:
1) FBC, U+E, renal function, Ca, LFT and ESR,
2) blood pressure is mandatory
Imaging:
1) RUSS can distinguish between cystic, solid and complex renal lesions
2) Complex cysts seen on USS should be further investigated with CT and classified according to the Bosniak classification - Bosniak I and II cysts can be safely ignored, Bosniak III or IV cysts require surgical exploration
3) Contrast enhanced CT chest/abdo/pelvis is the gold standard for staging renal tumours
- Hounsfield units measure the degree of enhancement when the kidney is viewed in pre and post contrast phases. A renal malignancy should enhance a minimum change of 20 Housnfield units
4) MRI/ Doppler can be used to assess infiltration into the renal vein
- MRI can be used to investigate renal lesions where the use of nephrotoxic contrast in contraindicated
NB - imaging is not 100% diagnostic, only histological diagnosis can truly confirm the presence of cancer
What size renal lesion is safe to offer surveillance for?
Surveillance of localised renal lesions of less than 4cm in diameter with imaging alone may be appropriate. Incidental small tumours found in the elderly or patients with significant co-morbidities may be watched because they are unlikely to cause morbidity and mortality earlier than the patients pre-existing conditions.
Intervention can be considered for fast growing tumours or those that are symptomatic.
What is the gold standard treatment of small localised tumours?
Radical nephrectomy (removal of the whole kidney covered in Gerota’s fascia) or partial nephrectomy (removal of part of the kidney) may be performed using a variety of techniques.
Essentially, a T1 tumour less than 7cm is amenable to laparascopic radical nephrectomy. Larger, localised tumours may be considered for minimally invasive surgery or open removal.
What are the complications of nephrectomy?
- injury to GI organs - e.g. spleen, liver, pancreas, bowel
- bleeding from major vessels - renal artery, renal vein, IVC aorta
- pleural injury - pneumothorax
- ileus
- renal failure
- early or late infection
- systemic complications - PE, DVT, MI
- incisional hernia
How are large renal tumours managed?
Open radical nephrectomy is reserved for the removal of large tumours over 7cm in diameter, with or without evidence of ipsilateral adrenal or nodal tumour involvement.
This may be performed via loin, abdominal, or thoraco-abdominal incision. Tumours with renal vein, or IVC infiltration may require cardiac bypass during the procedure.
How is metastatic RCC managed?
Patients with metastatic disease carries a poor prognosis. If patients have single organ metastasis and good performance then radical nephrectomy with metastectomy may be curative.
Metastatic disease is managed using anti-angiogenesis agents. RCTs show that tyrosine kinase inhibitors (e.g. Sunitinib) and mammalian target of rapamycin inhibitors (e.g. Temsirolimus) prolong progression free survival in patients with metastatic RCC by 3-6 months.
