title: Characteristic MRI findings of sarcomatoid renal cell carcinoma dedifferentiated from clear cell renal carcinoma: radiological-pathological correlation.
abstract: OBJECTIVE
  To evaluate MRI findings of sarcomatoid renal cell carcinoma (SRCC).
  
  
  METHODS
  Eleven patients with pathologically proven SRCC dedifferentiated from clear cell renal carcinoma (CCRC) underwent preoperative renal MRI. The MRI findings were compared with histological findings. On MRI, the following findings were evaluated: the presence and distribution of areas showing heterogeneous iso to high signal intensity (SI) on T2-weighted images (T2HIA) and conspicuously low SI areas (T2LIA) compared to normal renal cortex, areas showing high SI on T1-weighted images and unenhanced areas on dynamic contrast-enhanced images, disruption of pseudocapsule, and the SIs of T2HIA and T2LIA on diffusion-weighted imaging (DWI). The apparent diffusion coefficient (ADC) values and SI ratios to muscle on dynamic contrast-enhanced imaging (DCE) were compared between T2HIA and T2LIA using the t test.
  
  
  RESULTS
  The distribution of T2HIA and T2LIA was as follows: a mixed pattern alone in five, nodular T2LIA pattern alone in one, both mixed and nodular T2LIA patterns in four, and a separated pattern in one. Disruption of the pseudocapsule was seen in all cases. The imaging findings suggesting intratumoral hemorrhage and necrosis were seen in 18% and 63%, respectively. The SIs of T2HIA and T2LIA were low intermediate and high on DWI, respectively. T2LIA and T2HIA corresponded to the components of SRCC with abundant fibrosis and CCRC, respectively. T2LIA showed significantly lower enhancement at all DCE phases and a lower ADC value than T2HIA.
  
  
  CONCLUSIONS
  The presence of T2LIA corresponding to the area showing a hypovascular nature and markedly restricted diffusion might be characteristic findings of SRCC. Intratumoral hemorrhage and necrosis were seen, but they were not specific findings.
authors.affiliation: Department of Radiology, Nagoya City University Graduate School of Medical Sciences and Medical, school. Electronic address: m2rbimn@gmail.com.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Misugi
authors.initials: M
authors.lastname: Urano
authors.forename: Masaki
authors.initials: M
authors.lastname: Hara
authors.forename: Yukio
authors.initials: Y
authors.lastname: Fujiyoshi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inagaki
authors.forename: Yuta
authors.initials: Y
authors.lastname: Shibamoto
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000473:pathology; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007668:Kidney / Q000473:pathology*; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged
chemical_list: D003287:Contrast Media
keywords: Clear cell renal carcinoma; Diffusion-weighted MRI; Dynamic contrast-enhanced imaging; Sarcomatoid renal cell carcinoma; T2-weighted imaging