A 42-Year-Old Office Assistant With Chronic Leg and Back Pain

John G. Christensen, Jr, MD


March 05, 2021


The CT scan with and without contrast reveals a 2-cm, solid, enhancing, right lower pole exophytic mass confined to the kidney and no enlarged lymph nodes or signs of metastasis. No fat content by CT scan criteria is noted.

Only 20% of small solid renal masses that are suspicious for renal cell carcinoma (RCC) on CT scan are benign (oncocytoma or atypical, fat-poor angiomyolipoma); 60% are relatively indolent RCCs, and about 20% demonstrate potentially aggressive histologic features, making RCC the most likely diagnostic option above, given the findings presented.[1] The incidence of more aggressive cell types increases in lesions over 3 cm.[2] Other causes of renal mass include abscess, angiomyolipoma, urothelial carcinoma, metastatic lesions to kidney, infarct or scar, vascular malformations, and pseudotumor.

More than 50% of RCCs are now found incidentally in asymptomatic patients undergoing imaging for other purposes. Most of these are T1 (7 cm or smaller, confined to the kidney). The "classic triad" of flank pain, flank mass, and hematuria occurs in 10% of cases and is indicative of advanced disease.[3] The individual components are seen more frequently, with hematuria present in 40% of presentations, flank pain present in 40%, and a palpable mass present in 25%. Other presenting symptoms include weight loss, fever, hypertension, hypercalcemia, night sweats, malaise, abnormal liver function test results (not necessarily indicative of metastatic disease to the liver), and varicocele (especially left side due to spermatic vein compression).[3]

RCC occurs at an annual rate of about 17 new cases per 100,000 population in the United States, with an average age at diagnosis in the early 60s. Overall, about 35% of patients diagnosed with RCC eventually succumb to the disease. The stage at presentation strongly affects survival and cure rates.

The risk of developing RCC may be reduced through fruit, vegetable, and fatty fish consumption and by moderate alcohol consumption. Cigarette smoking doubles the risk for RCC and may contribute to as many as one third of all cases. Obesity is also a significant risk factor. Family history is also associated with increased risk for RCC. At least four hereditary syndromes are associated with RCC: von Hippel-Lindau syndrome, hereditary papillary renal carcinoma, familial renal oncocytoma associated with Birt-Hogg-Dube syndrome, and hereditary renal carcinoma.[3] Long-term dialysis, especially with acquired cystic disease of the kidney, is associated with an increased risk of developing RCC.


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