Benign pathological findings in 303 Chinese patients undergoing surgery for presumed localized renal cell carcinoma

Abstract

Objective: To analyze the incidence of benign lesions in Chinese patients undergoing nephrectomies for renal masses identified as localized renal cell carcinoma (RCC) in preoperative imaging. Methods: Between 1999 and 2007, 303 patients (112 female, 191 male) with presumed localized RCC underwent nephrectomy (234 radical nephrectomies and 69 partial nephrectomies). Preoperative computed tomography images and pathological findings were reviewed and analyzed. Results: Pathological examinations revealed 31 (10.2%) benign lesions in the 303 patients. Among these 31 benign lesions, 15 (5.0%) were angiomyolipomas (AML) and only four (1.3%) were oncocytomas. Significantly, 20 (17.9%) of the 112 female patients had benign lesions compared with 11 (5.8%; P = 0.001) male patients. Benign renal lesions were found in five (25.0%) of the 20 patients with renal masses smaller than 2 cm, 13 (13.0%) of the 100 patients with renal masses 2-4 cm in size and 13 (7.1%) of the 183 patients with renal masses larger than 4 cm. Conclusions: Patients in the present study population show a low incidence of benign renal lesions, approximately half of them being AML. Female patients and patients with renal masses smaller than 4 cm are more likely to have benign renal lesions.

Diagnostic accuracy of pre-operative imaging findings in presumed clinical T1a renal cell carcinomas

“…Previous studies indicated that 12.4-30.0% of tumors smaller than 2 cm were benign compared with 4.8-20.9% of those larger than 2 cm in cases with small renal masses presumed to be T1a RCC (5,6,(19)(20)(21)(22)(23). Furthermore, the incidence of benign pathological lesions in the renal tumors of ≤20 mm in diameter was significantly higher (12.7%) than in tumors >20 mm (3.9%) in the present series.…”

“…Fujii et al suggested that one possible reason for the lower incidence of benign pathological findings in Asian than Western countries was the low incidence rate of oncocytoma in Asia (7), which is indistinguishable from RCC using the present imaging modalities (24). The reported incidence rates of oncocytoma in small renal masses were 5.7-10.7% in Western countries (5,6,19-22) but 1.3-2.8% in Asian countries (7,8,23), consistent with the results of the present study (1.5%). Although further studies in various countries are required, these observations suggest that there may be ethnic differences in the oncocytoma incidence rate.…”

“…The incidence rates of benign pathological lesions at nephrectomy for presumed small RCC have been reported previously (5)(6)(7)(8)(19)(20)(21)(22)(23). Various incidence rates were reported, and differences were indicated based on ethnicity.…”

“…Various incidence rates were reported, and differences were indicated based on ethnicity. The reported incidences of benign pathological lesions with a tumor diameter of ≤40 mm were 17.3-23.4% in studies from Western countries (5,6,(19)(20)(21)(22)) and 7.1-15.0% in studies from Asian countries (7,8,23). Fujii et al suggested that one possible reason for the lower incidence of benign pathological findings in Asian than Western countries was the low incidence rate of oncocytoma in Asia (7), which is indistinguishable from RCC using the present imaging modalities (24).…”

Diagnostic utility of diffusion-weighted magnetic resonance imaging in two common renal tumors

“…Renal angiomyolipoma usually contains significant fat and therefore, shows typical characteristics of fat on CT or MRI. The differential diagnosis of renal carcinoma is usually not difficult, but lesions with little or no fat and small tumors are difficult to discern on conventional CT, plain MRI and contrast-enhanced imaging (3)(4)(5). In addition, certain patients are allergic to the contrast material used during enhanced CT (6,7).…”