Key Clinical Questions
What are the most common presenting signs of renal tumors?
How are renal tumors diagnosed?
How do renal pelvis and ureteral tumors present?
Which specialists should be involved in the care of renal tumors and their complications?
Renal masses may represent renal cell carcinoma, metastasis from other malignancies, lymphoma, or benign tumors such as angiomyolipoma (AML), oncocytomas, benign complex cystic structures or adenomas. Occasionally, focal pyelonephritis or infiltration of a renal pelvis malignancy may mimic the appearance of a primary renal mass on imaging studies and must be considered in the appropriate clinical setting. Renal masses of one form or another can be found in an estimated 50% of all patients over age 50. Small renal masses, defined generally as those <4 cm in size (see Figure 180-1), represent a large proportion of incidentally discovered renal neoplasms and can present a management dilemma for the urologist and oncologist given a sometimes unclear natural history.
Exophytic small renal mass of the left kidney highly suspicious for primary renal cell carcinoma.
Renal cell carcinoma (RCC) accounts for approximately 3% of all adult malignancies in the United States with approximately 65,000 cases per year and accounts for approximately 14,000 deaths per year. This incidence represents a doubling in the rate of newly diagnosed RCC over the past 10 years and likely reflects an increased rate of detection due to increased utilization of ultrasound and high-resolution computed tomography (CT) scan for the evaluation of abdominal complaints.
According to the Surveillance, Epidemiology and End Results (SEER) database from 2008 to 2012, RCC occurs more commonly in men than women (approximately 2:1), with a median age of 64 years and is found to be metastatic in approximately 17% of patients at time of diagnosis. Of patients diagnosed with kidney-confined disease (approximately 65% at diagnosis), 92% will have a 5-year survival rate.
The most common type of RCC is clear cell carcinoma comprising approximately 80% of all RCCs. Other subtypes include papillary (types I and II), chromophobe, collecting duct, medullary, and translocation tumors. Some tumors develop more aggressive features and can have sarcomatoid or rhabdoid histological features. Poorly differentiated tumors often act very clinically aggressive.
While the majority of cases of RCC are sporadic, approximately 2% to 3% are felt to be genetic in origin. Many familial syndromes involving RCC have been described in the literature. The most common among these is von Hippel-Lindau syndrome which is characterized by hemangioblastomas of the central nervous system, retinal angiomas, pheochromocytoma, and RCC of the clear cell subtype. Other familial syndromes include hereditary papillary RCC, familial leiomyomatosis and RCC, and Birt-Hogg-Dube syndrome. Patients with a strong family history of renal malignancies warrant a comprehensive history and physical to screen for associated disease processes.