versión impresa ISSN 1677-5538
Int. braz j urol. vol.37 no.6 Rio de Janeiro nov./dic. 2011
Characterization of small solid renal lesions: can benign and malignant tumors be differentiated with CT?
Millet I; Doyon FC; Hoa D; Thuret R; Merigeaud S; Serre I; Taourel P
Department of Radiology, CHU Lapeyronie, 371 Ave du Doyen Gaston Giraud, 34295 Montpellier, France
AJR Am J Roentgenol. 2011; 197: 887-96
OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of CT in determining whether a small solid renal enhancing mass is benign or malignant.
MATERIALS AND METHODS: Ninety-nine biopsies of enhancing solid renal masses 4 cm or smaller without fat on CT scans were performed under CT fluoroscopic guidance. The growth pattern, interface with parenchyma, presence of a scar and segmental inversion enhancement, unenhanced CT histogram, and pattern and degree of enhancement on triphasic MDCT images were independently evaluated by two radiologists. Biopsy and pathology reports were used as the reference standard, and imaging follow-up of benign lesions was performed for at least 1 year. Statistical analysis was performed to determine the significance of CT criteria in differentiating malignant from benign lesions.
RESULTS: Of the 99 lesions, 74 (75%) were malignant at biopsy, and 25 (25%) were benign. Lesions with gradual enhancement were more likely to be benign. No significant correlation was found between other CT features and a malignant or benign diagnosis. The sensitivity, specificity, and positive and negative predictive values of progressive enhancement for a diagnosis of benignity were 60%, 73%, 43%, and 84%.
CONCLUSION: In the evaluation of enhancing small solid renal lesions without fat, no CT criteria were of substantial help in differentiating malignant from benign lesions.
Pre-operative characterization of small solid enhancing renal lesion containing no macroscopic fat is a difficult task. Although the CT characteristics of benign solid renal lesion overlap with those of renal cell carcinoma, we encourage radiologists from our institution to narrow the differential diagnosis whenever it is possible. The pre-operative radiologic impression of renal tumor histology is of particular value when affects therapeutic management. During the nephrographic (90-100 seconds) and excretory phase (180 seconds), some renal tumors subtypes demonstrate significant different degrees of enhancement. Clear cell of renal carcinoma can be suggested by the presence of strong and heterogeneous contrast enhancement and rapid washout. Papillary renal cell carcinoma is usually homogeneously hipovascular similarly to the rare benign metanephric adenoma. Solid homogeneously hypervascular renal mass can be observed in oncocytoma and angiomyolipoma without macroscopic fat. Thus, depending on the clinical scenario, percutaneous biopsy is performed particularly when its results will influence therapeutic management
Dr. Adilson Prando
Head, Department of Radiology and
Diagnostic Imaging, Vera Cruz Hospital
Campinas, São Paulo, Brazil