title: Chromophobe renal cell carcinoma: multiphase MDCT enhancement patterns and morphologic features.
abstract: OBJECTIVE
  The purpose of this investigation is to retrospectively describe morphologic features, enhancement characteristics, and clinical outcomes in a series of pathologically proven chromophobe renal cell carcinomas (RCCs).
  
  
  METHODS
  Thirty-five patients who were imaged at a single institution between 2005 and 2012 with pathologically proven chromophobe RCC were identified, all of whom underwent preoperative renal protocol CT (unenhanced, arterial, venous, and delayed images). The morphologic characteristics of each tumor (e.g., necrosis, tumor composition, and calcification), as well as attenuation values (in Hounsfield units) of the tumor, aorta, inferior vena cava, and kidney were evaluated by a board-certified radiologist. In addition, information regarding patient demographics and survival was obtained by a separate radiologist from the electronic medical record.
  
  
  RESULTS
  Sixty percent of the patients were men, with a mean age of 60.2 years. Forty-six percent of cases were incidentally identified, without patient symptoms. None of the patients had evidence of distant metastatic disease, either on initial staging CT or over the course of follow-up (mean, 2.0 years). Mean maximal tumor diameter was 5.24 cm. Forty-six percent of tumors were homogeneous, 85% of lesions were either completely solid or mostly solid, 14% showed calcifications, and 34% showed a central scar or necrosis. Mean maximum attenuation values were 87.9 HU (arterial phase), 83.9 HU (venous phase), and 60.6 HU (delayed phase), with an average delayed washout of 31%. Tumor-to-cortex ratios for the three enhanced phases were 0.59, 0.48, and 0.50, respectively.
  
  
  CONCLUSIONS
  Chromophobe RCCs were found to have a wider variability of CT features than previously reported, although they do have a greater propensity for homogeneity and the presence of a central scar or necrosis. Their enhancement characteristics fall in between those of clear cell and papillary RCC, although there is considerable overlap.
authors.affiliation: 1 Department of Radiology, Johns Hopkins University, JHOC 3251, 601 N Caroline St, Baltimore, MD 21287.
authors.forename: Siva P
authors.initials: SP
authors.lastname: Raman
authors.forename: Pamela T
authors.initials: PT
authors.lastname: Johnson
authors.forename: Mohamad E
authors.initials: ME
authors.lastname: Allaf
authors.forename: George
authors.initials: G
authors.lastname: Netto
authors.forename: Elliot K
authors.initials: EK
authors.lastname: Fishman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*