CHAPTER 37 Renal Tumors, Adults
How quickly is the incidence of renal cell cancer increasing?
Two percent annually. Although renal cancer is more common in men, the incidence in women is rising faster (2.2% vs 1.7%). The greatest increase has been noted in tumors <4 cm in diameter.
What is the incidence of renal cell carcinoma (RCC)?
Renal cell cancer accounts for 3% of adult malignancies. Approximately 65,000 new cases of RCC are expected to be diagnosed in 2012, with approximately 14,000 RCC-related deaths. RCC accounts for up to 90% of all kidney tumors.
What are the risk factors for RCC?
Tobacco use, hypertension, obesity, male gender, and urban dwellers. The majority of RCC occur in the 5th to 7th decade of life; however, a recent trend suggests a higher incidence in younger females and adolescents.
What is the typical clinical presentation for most RCC cases and how does it differ from the classic triad?
Incidental in the modern era. Hematuria (gross or microscopic), mass, and flank pain are not uncommon. The classic triad of pain, hematuria, and flank mass occurs in only 10% to 15% of patients. Presenting symptoms can often be attributed to metastasis or paraneoplastic syndromes.
What is responsible for the increased detection of incidental renal tumors?
The routine use of cross-sectional imaging (CT scans) to evaluate abdominal symptomatology.
What must be considered prior to the administration of IV contrast in the evaluation of renal mass?
Renal function. Impaired renal function places patients at risk for complications following the administration of iodine and gadolinium-based contrast agents. Iodine-based contrast is associated with the risk of acute nephrotoxicity and worsening renal function. Gadolinium has been associated with nephrogenic systemic fibrosis.
What are Hounsfield units and how do they help to differentiate renal tumors on computed tomography?
Hounsfield units are a measure of radiodensity on CT scans. Enhancement of 15 or more Hounsfield units following the administration of contrast are suggestive of a malignancy; however, benign lesions such as oncocytoma will also enhance. Whereas, tumors containing areas with negative Hounsfield units, suggestive of fat, are likely angiomyolipomas (AMLs).
Can information from a percutaneous needle biopsy of a renal mass be considered reliable?
Analysis of biopsies on permanent section is significantly more reliable than frozen-section analysis. With experienced pathologists and radiologists, the expected sensitivity and specificity of a percutaneous needle biopsy is 97% and 100%, respectively. The primary limitation of renal mass biopsy in contemporary series is nondiagnostic biopsies, not false negatives.
What are the indications for a biopsy of a renal mass?
Percutaneous biopsy is advocated only when clinical or radiologic evidence suggests a diagnosis other than RCC (such as lymphoma or metastases from another primary tumor), or when a definite diagnosis is absolutely necessary. However with the improved accuracy of renal mass biopsy, its role may be expanding to help guide treatment decisions in patients with small renal tumors.
How is renal cancer staged?
By TNM staging system.
• T1a: confined to the kidney <4 cm.
• T1b: confined to the kidney >4 cm and <7 cm.
• T2a: confined to the kidney >7 cm and <10 cm.
• T2b: confined to the kidney and >10 cm.
• T3a: perinephric fat, ipsilateral adrenal gland involvement, and tumor extends into the renal vein or segmental branches.
• T3b: tumor extension into the vena cava, but not extending above the diaphragm.
• T3c: tumor extension into the renal vein extending above the diaphragm or invasion into the wall of the vena cava.
• T4: tumor extension beyond Gerota fascia, involvement of adjacent organs other than the ipsilateral adrenal gland.
What is the standard of care in the treatment of renal tumors clinically localized to the kidney?
Nephrectomy—partial or radical.
What are additional treatment options for patients with T1a tumors?
Observation, cryoablation, and radiofrequency ablation.
Synchronous metastases occur in what percentage of RCC patients?
Up to one-third of patients will have synchronous metastases. Metachronous metastases occur in 10% to 20% of patients at 5-year follow-up. The prognosis is much worse for patients with synchronous metastasis.
How frequently does RCC invade adjacent organs?
RCC invades adjacent organs in approximately 10% of cases. Invasion of adjacent organs is associated with a very poor prognosis with reported 5-year survival rates of less than 5%. In many cases, surgical intervention can require partial resection of contiguous structures including colon, pancreas, liver, or spleen. Preoperative imaging often overstates the possibility of direct liver invasion.
A patient undergoes a partial nephrectomy for organ-confined RCC. What recurrence rates would be expected in the ipsilateral kidney and the contralateral kidney?
Recurrence in the ipsilateral kidney would be 1% to 5% and 1% to 3% in the contralateral kidney.
What percentage of RCCs occur bilaterally?
One to five percent of RCC patients have tumors present in both kidneys simultaneously.
What is the incidence of the different histologic types of RCC?
Clear cell (80%) followed by papillary (15%), chromophobe (5%), collecting duct cancer (1%), and renal medullary carcinoma (< 1%).
What is the prognosis for cystic clear cell RCC?
Excellent. Cystic clear cell RCC is associated with a low rate of systemic progression following complete surgical excision.
True/False: At least 50% of RCCs are vimentin-positive on immunohistochemical analysis.
True. In addition, high-grade tumors, clear cell cancers, and those with sarcomatoid differentiation are more commonly vimentin-positive. Almost all RCCs stain positively for keratin 8 and 18 and the majority stains positively for epithelial membrane antigen. This is useful in diagnosing metastases.
What cystic renal diseases are associated with an increased incidence of RCC?
Acquired renal cystic disease is associated with a 4- to 6-fold increased risk of RCC over the general population. Von Hippel–Lindau (VHL) disease has a known incidence of bilateral renal cysts in 76% of affected individuals with a 35% to 38% incidence of RCC in affected individuals. Tuberous sclerosis is associated with a 2% increased risk of RCC over the general population.
Which types of RCC are more aggressive?
Renal medullary carcinoma and collecting duct carcinoma are more aggressive subtypes. The behavior of clear cell, papillary, and chromophobe types are best predicted by stage and grade.
Which type of RCC is associated with multifocality?
Papillary RCC is associated with a 15% incidence of multifocality within the affected kidney.
What is the predominant group of patients in whom the renal medullary type of RCC appears?
Renal medullary carcinomas occur almost exclusively in association with sickle cell trait or hemoglobin SC disease. These are very aggressive tumors and tend to occur in younger patients.
What is the renal cell type of origin of clear cell and papillary RCCs?
Proximal convoluted tubule.
What is the renal cell type of origin of Bellini tumors?
The origin of the Bellini tumors is the collecting duct. Renal medullary carcinomas are thought to arise from the calyceal epithelium.
List the hereditary forms of RCC?
Von Hippel–Lindau (VHL) disease, Birt–Hogg–Dube (BHD), hereditary papillary RCC, and hereditary leiomyomatosis and RCC syndrome.
What percentage of RCCs are familial?
Only 2% to 3%, the majority are considered sporadic.
What are the specific genetic abnormalities associated with each of the hereditary forms of RCC?
• VHL: VHL gene on chromosome 3p.
• Birt–Hogg–Dube: BHD1 gene on chromosome 17p.
• Hereditary papillary RCC: c-met protooncogene on chromosome 7q.
• Hereditary leiomyomatosis and RCC: fumarate hydratase on chromosome 1q.
What is Von Hippel-Lindau disease?
A rare, autosomal dominant, multiorgan syndrome associated with a 50% incidence of RCC; 75% incidence of renal, epididymal, and pancreatic cysts; cerebellar hemangioblastomas; retinal angiomas; and pheochromocytoma. Typically, RCC in this instance tends to be multiple and bilateral (80%). Historically, one-third of patients die from RCC.
What is the most common cause of hereditary pheochromocytoma?
VHL syndrome.
Can the size or appearance of renal lesions in VHL disease predict the presence of RCC?
No. No correlation exists between the size of a lesion and the diagnosis of RCC. Twenty-five to thirty-five percent of RCC in VHL occur in cystic lesions.
A patient with VHL has small bilateral renal tumors. At what point is surgical intervention indicated?
The balance between oncologic control and preservation of renal function is crucial in patients with small renal tumors. In VHL patients, tumors less than 3 cm have been associated with a low rate of progression to metastatic disease. For this reason, close surveillance with surgical intervention when a tumor reaches 3 cm in size can be employed in this population.
A patient with VHL has diffuse, high-volume, bilateral renal lesions. What treatment is best?
The best treatment in this case would be bilateral nephrectomy with subsequent transplantation. Nephron-sparing surgery, while technically feasible in many cases, is best reserved for patients with cystic and low-volume, nondiffuse solid lesions.
What is the function of the VHL gene?
The VHL gene is a tumor suppressor gene. The VHL protein complex helps to maintain appropriate levels of HIF-1, depending on oxygen availability. When VHL is mutated, HIF-1 levels increase, leading to the activation of angiogenesis pathways.
Do sporadic clear cell RCC have mutations of the VHL gene?
Yes, 50% to 60% of clear cell RCC have mutations of the VHL gene. Another 15% to 20% have hypermethylation of the VHL gene.
Describe Birt-Hogg-Dube syndrome (BHD).
Autosomal dominant disorder characterized by cutaneous fibrofolliculomas, lung cysts, and renal tumors. Renal tumors are noted in approximately 30% of patients with BHD syndrome. The most common renal tumors are oncocytomas and chromophobe RCC; these tumors are often multifocal and bilateral.
Describe hereditary papillary RCC syndrome (HPRCC).
Autosomal dominant disorder characterized by bilateral multifocal type 1 papillary tumors.
Describe hereditary leiomyomatosis and RCC syndrome (HLRCC).
Autosomal dominant disorder characterized by type 2 papillary tumors and cutaneous and uterine leiomyomas. Although only 20% to 30% of patients with HLRCC syndrome develop renal tumors, the tumors have been noted to be very aggressive.
What accounts for the yellowish gross appearance of many clear cell RCCs?
The presence of cholesterol causes the gross yellow appearance of these tumors. The lipid substances tend to dissolve during histologic preparation, creating the microscopic appearance of clear cells.
True/False: Nuclear grade is a predictor of survival that is independent of pathologic stage.
True. Nuclear grade has a significant impact on survival for all stages of RCC.
Differentiate between the Bosniak classification of renal cysts and their relationship to malignancy.
• Category I: A simple cyst with through transmission on ultrasound and a clearly defined wall. There are no internal septa, echoes, or calcifications. This portends a remote chance for cancer.
• Category II: A septated, nonenhancing cyst that can have thin peripheral calcifications and minimally thickened wall. This lesion carries roughly a 15% chance of malignancy.
• Category III: A complex cyst with a thickened wall, a hyperdense cyst that shows no enhancement with contrast administration, can have thick calcifications, or thickened septa that carry roughly a 50% cancer.
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