Renal collecting duct carcinoma: imaging spectrum with CT and MRI / 中华泌尿外科杂志

ABSTRACT

Objective To summarize the experience of using CT and MRI to diagnose the renal collecting duct carcinoma.Methods From February 2005 to January 2012,10 cases with renal collecting duct carcinoma,confirmed by pathology,were reviewed retrospectively.The data contained 6 men and 4 women,whose age ranged from 21 to 62 years (mean age 48 years).The flank pain was complained by 7 cases,waist discomfort was complained by 3 cases.In urine laboratory test,positive urine erythrocytes (++++) were found in 6 cases.In 10 cases,7 cases accepted CT examination and 3 cases accepted MRI examination.The growth pattern,lesion location,dynamic enhanced scan phase of the tumor and the way of spreading and metastasis were analyzed based on those CT and MRI images.Results The lesions were located in the left kidney in 6 cases,located in the right kidney in 4 cases.The size of tumors ranged from 4.4 cm×5.8 cm to 7.2 cm× 7.4 cm (mean size 5.7 cm× 6.4 cm).The mass,located in the center of renal parenchyma with irregular shape,showed infiltrative growth pattern.The shape of kidney was normal,whereas the border line between cortex and medulla was indistinct.The tumor involved the renal cortex and medulla in 4cases and involved the renal cortex,medulla,pelvis simultaneously in 6 cases.Among 7 patients who accepted the CT scanning,the solid mass was revealed in 6 cases.On CT plain scanning,the masses demonstrated slightly low or equal density within flaky or patchy low-density necrosis.Two cases showed small punctate calcification within the mass.One case was solid and cystic mass,which the cystic part of the mass showed irregular shape of the liquid-density.Among 3 patients accepted MRI scanning,all masses showed solid characters.The substantial part showed slightly hypointense on T1WI and low signal intensity on T2WI.The necrotic foci demonstrated low signal intensity on T1WI and high signal on T2WI.Dynamic enhanced scan revealed mild to moderate enhanced in the substantive part.The density of signal was lower than the renal cortex and slightly higher than the renal medulla in corticomedullary phase.It enhanced continuously in parenchymal phase,but still lower than the renal parenchyma.It enhanced continuously in the delayed phase,while the cystic or necrotic lesions were not observed the enhancement.Renal artery was surrounded by the mass in 2 cases.Tumor embolus was found in the renal vein in 2 cases,9 cases were noticed with renal hilum and paraortic hyperlymphonodus.The thoracic and lumbar spinal metastasis was found in 1 case and adrenal metastasis was found in another case.All patients underwent radical nephrectomy,that pathological diagnosis was renal collecting duct carcinoma.Conclusions The CT and MRI imaging characteristics of renal collecting duct carcinoma can be described as the mass located in the center of renal parenchyma with the infiltrative growth pattern.In MRI image,it demonstrates low signal intensity on T2WI.And a mild continuously enhanced can be observed on dynamic enhanced scanning.Moreover,the tumor often involves renal hilum,perirenal fat capsule,paraortic lymph node,and shows the tendency of distant metastasis.