Comparative study of CT appearances in renal carcinoma associated with Xp11.2 translocation/TFE gene fusion and papillary renal cell carcinoma

Abstract

ObjectivesRenal cell carcinoma associated with Xp11.2 translocation and TFE gene fusion (Xp11.2/TFE RCC), and papillary renal cell carcinoma (PRCC) are uncommon subtypes of renal cell carcinoma. This study investigated the multi-slice CT (MSCT) characteristics of these two tumor types. Methods12 patients with Xp11.2/TFE RCC and 18 patients with PRCC were studied retrospectively. MSCT was undertaken to investigate differences in tumor characteristics and enhancement patterns. Results12 patients with Xp11.2/TFE RCC and 18 patients with PRCC, tumors (mean diameter 5.0±2.5cm vs 4.6±1.7cm, P>0.05), solitary (12 vs 14, P>0.05), solid (12 vs 15, P>0.05), cystic components (2 vs 11, P<0.05), calcification (0 vs 6, P<0.05), hemorrhage (9 vs 5, P<0.05), had a clear boundary (capsule sign, 12 vs 17, P>0.05), were centered in the renal medulla (9 vs 16, P>0.05), impressed upon the renal pelvis (6 vs 11, P>0.05), homogeneous enhancement (10 vs 7, P<0.05) and uncommonly had lymph node (2 vs 0) or hepatic metastasis (1 vs 0) (P<0.05). The density of Xp11.2/TFE RCC tumors was greater than that of PRCC tumors, normal renal cortex or medulla on unenhanced CT (49.8±5.3 vs 41.4±2.4, 37.6±5.1 or 32.6±4.1, respectively, P<0.05). Enhancement was higher with Xp11.2/TFE RCC than with PRCC tumors during all phases. Xp11.2/TFE RCC enhancement was higher than in the renal medulla during cortical and medullary phase but lower than in normal renal medulla during the delayed phase. PRCC tumor enhancement was lower than that for normal renal medulla during all enhanced phases. ConclusionBoth tumor types originated from the renal medulla. Distinguishing features included density on unenhanced CT, calcification, enhancement patterns, etc. Identifying these differences may aid diagnosis.