Keywords:
Abdomen, Kidney, CT, Contrast agent-intravenous, Cancer
Authors:
Y. Ogawa, S. Morita, T. Takagi, K. Yoshida, K. Tanabe, Y. Nagashima, Y. Nishina, S. Sakai; Tokyo/JP
DOI:
10.26044/ecr2021/C-11231
Purpose
A peritumoral pseudocapsule, composed of fibrous connective tissue and compressed adjacent renal parenchyma, is frequently observed in renal cell carcinoma (RCC) pathologically [1]. Compared to MRI, CT is less sensitive in detecting pseudocapsules [2,3]. Some reports define a high-attenuation rim in the contrast-enhanced CT images including the early phase as a sign of a pseudocapsule [4,5]. The findings of a pseudocapsule on CT are confusing as fibrous tissue must not be enhanced in the early phase images, and have room for improvement.
We found that unenhanced thin lines are often observed at the tumor-renal cortex border on the corticomedullary phase CT images in clear cell RCC (ccRCC), which are not observed in fat poor angiomyolipoma (Fp-AML). We named this finding the “early dark cortical band” (EDCB). We hypothesized that the EDCB was a sign of a peritumoral pseudocapsule in RCC. Thus, this study aimed to retrospectively evaluate the frequency of the EDCB on CT in renal tumors and whether this sign could be a predictor to differentiate ccRCC from Fp-AML, and whether it could detect peritumoral pseudocapsules.