Small renal cell carcinoma: MRI with pathologic correlation

Abstract

The MRI features of small renal cell carcinomas (RCCs) were retrospectively reviewed and correlated with histology in 24 patients. MRI features on both T1- and T2-weighted images were classified into hypointensity, isointensity, and hyperintensity. Each tumor was pathologically classified into four types: alveolar, papillary, tubular, and cystic. These findings were correlated with MR signal intensities. Alveolar tumors showed hypointensity to isointensity on T1-weighted image and isointensity to hyperintensity on T2-weighted image. In contrast, all papillary tumors showed hypointensity on T2-weighted image. Four of six tumors with hypointensity on T2-weighted image were caused by hemosiderin deposition, hemorrhage, and necrosis. However, there were two papillary RCCs that showed hypointensity on T2-weighted image despite no hemosiderin deposition and no hemorrhage. We conclude that papillary RCC is associated with T2-hypointense appearance as well as hemosiderin deposition, hemorrhage, and necrosis.

MR Imaging of papillary renal neoplasms: potential application for characterization of small renal masses

“…The presence of iron in RCC secondary to hemorrhage is not uncommon, but it is not necessarily related to hemorrhage, but to reactive changes in the lymphoreticular system. Ferritin has been shown to occur primarily within the cytoplasm of carcinomatous cells themselves [25]. The low signal intensity could have another explanation secondary to the densely collageneous, relatively marked hypocellular nature of the tumor with a background of collagen.…”

Papillary renal cell carcinoma in allograft kidney

“…A renal mass that appears hypointense relative to normal renal parenchyma on both T1-and T2-weighted images is rare. A small number of papillary renal cell cancers studied by MRI have been described previously as having hypointensity on T2-weighted images [15]. This markedly observed low signal intensity on T2-weighted images has been attributed to the paramagnetic effect of the abundant hemosiderin deposition localized within the tumor cells [10].…”

Renal angiomyoadenomatous tumour: Imaging features

“…The two most common are papillary RCC and angiomyolipoma with minimal fat. The low T2 signal of papillary carcinoma is welldocumented [8][9][10] and has been shown to be due to papillary architecture with contribution from the presence of hemosiderin in some cases. 8 However, papillary renal cell carcinoma typically is hypovascular and does not enhance markedly as seen in this case.…”

“…13 Other enhancing masses that may demonstrate a low signal on T2-weighted imaging include capsular leiomyoma, 14,15 metanephric adenoma, 16 solitary fibrous tumour 17 and mucinous tubular and spindle cell carcinoma of the kidney. 18 Finally, clear cell RCC is typically hyperintense on T2-weighted imaging, 19 but may demonstrate T2 hypointensity if it has undergone internal hemorrhage. Therefore, when an enhancing T2 hypointense mass is encountered, a percutaneous biopsy is recommended to differentiate between benign and malignant pathologies.…”