Clear cell renal cell carcinoma: identifying the gain of chromosome 20 on multiphasic MDCT

Purpose: To investigate whether multiphasic multidetector computed tomography (MDCT) enhancement can help identify the gain of chromosome 20 in clear cell renal cell carcinomas (RCCs), a rare prognostically significant cytogenetic abnormality. Methods: With the Institutional Review Board approval, we queried our institution’s pathology database to derive a cohort of 52 cases of clear cell RCC with preoperative four-phase renal mass protocol MDCT and karyotypes of the resected specimens during a 10-year period. Each lesion was evaluated for absolute and relative (compared to contralateral normal renal cortex) attenuations in each phase. Relative attenuation was calculated as [(lesion attenuation − cortex attenuation)/cortex attenuation] × 100. The absolute and relative attenuations were compared using t-tests. Results: Clear cell RCCs with the gain of 20 had significantly less nephrographic and excretory phase enhancement than clear cell RCCs without the gain of 20 (86.4 HU vs. 111.4 HU, p = 0.007; 70.0 HU vs. 89.4 HU, p = 0.003; respectively). Additionally, the relative nephrographic and excretory phase attenuations of clear cell RCCs with the gain of 20 were significantly less than that of clear cell RCCs without the gain of 20 (−52.7 vs. −34.7, p = 0.002; −44.9 vs. −31.1, p = 0.005; respectively). Conclusion: Multiphasic MDCT enhancement may assist in identifying the gain of chromosome 20 in clear cell RCCs, if validated in a large prospective trial.