Comparative Study On Spiral CT Features Of Different Subtypes Of Renal Cell Carcinoma

BackgroundRenal cell carcinoma is the most common tumor of parenchyma,including various subtypes originated from nephric tubule,there is a great discrepancy in clinical,pathological characteristic and prognosis among different subtypes.For lack of typical clinical characteristic,the radiological feature play a crucial role in preoperative prediction and prognosis estimation.With the widespread use of contrast-enhanced ultrasound,multislice spiral computed tomography (CT) and magnetic resonance imagine (MRI),combined with immunohistochemical, karyotype analysis and fluorescence in situ hybridization examination,the detection rate of renal cell carcinoma was large raised.Due to different histological appearance,the classification of renal cell carcinoma was further divided. Since renal cell carcinoma associated with Xp11.2 translocation/TFE gene fusion (Xp11.2 RCC) was introduced as a genetically distinct subtype into the WHO classification of renal neoplasms in 2004,there are few comparison among on radiological feature of different subtypes of non-clear cell renal cell carcinoma,which give rise to a debate on therapy.The study was aimed to evaluate the significance of spiral CT scan in differential diagnosis of different subtypes of renal cell carcinoma by investigating their CT features.ObjectiveTo investigate CT features of three subtypes of renal cell carcinoma so that to evaluate the significance of spiral CT scan in differential diagnosis of them.MethodsWe retrospectively analyzed the spiral CT data of 75 cases of renal cell carcinoma in our hospital from 2007 to 2014,which proved by postoperative pathology,these included 30 clear cell renal cell carcinoma (CCRCC),26 papillary renal cell carcinoma (PRCC),19 renal cell carcinoma associated with Xp11.2 translocation and TFE gene fusion (Xp11.2 RCC). All the patients were compared enhancement degrees and characteristics in plain CT scan and three phase (arterial,nephrographic and excretory phases) of enhancement.We compared enhancement degree of different subtypes of renal cell carcinoma by measuring the average enhanced CT value (the average CT value in maximum cross sectional area of arterial phase-the average CT value in maximum cross sectional area of plain CT scan) of them,the tumor size, enhancement pattern (homogeneous or heterogeneous), occurrence of necrotic or cystic components and calcifications were observed as well.Result1. The average enhanced CT value of CCRCC, PRCC and Xp11.2 RCC was (59.87± 29.21) HU,(28.88 ± 23.29) HU and (37.22 ± 35.96) HU,showing significantly statistical difference among the three subtypes in plain CT scan and arterial phase,as well as the average enhanced CT value (P<0.05),there is no significant difference in nephrographic and excretory phase (P>0.05).2. CCRCC showed greater signal intensity change than the other two in arterial phase (P<0.05),there is no significant difference in the degree of enhancement between PRCC and Xp11.2 RCC (P>0.05).3. The occurrence of necrotic or cystic components of CCRCC, PRCC and Xp11.2 RCC were in 23.3%、7.6%、52.6% of the patients, calcifications were observed in 0、 11.5%%、36.8% of the patients respectively,,showing significantly statistical difference among the three subtypes (P<0.05),while there was no difference in enhancement pattern (P>0.05).ConclusionCT features of different subtypes of renal cell carcinoma are helpful in diagnosis and preoperative prediction.The degree of enhancement is the most important parameter to differentiate the subtypes of renal cell carcinoma. The occurrence of necrotic or cystic components, calcifications and enhancement pattern can provide guidance in differentiating subtypes of renal cell carcinoma,and the clinical characteristics should be considered.The imaging diagnosis is vital part of clinical planning for renal cell carcinoma.