@Article{,
AUTHOR = {Anand V. Badri, Nikhil Waingankar, Kristin Edwards, Alexander Kutikov, Rosaleen B. Parsons, David Y. Chen, Marc C. Smaldone, Rosalia Viterbo, Richard E. Greenberg, Robert G. Uzzo},
TITLE = {Non-contrast imaging characteristics of papillary renal cell carcinoma: implications for diagnosis and subtyping},
JOURNAL = {Canadian Journal of Urology},
VOLUME = {26},
YEAR = {2019},
NUMBER = {5},
PAGES = {9916--9921},
URL = {http://www.techscience.com/CJU/v26n5/60488},
ISSN = {1488-5581},
ABSTRACT = {<b>Introduction:</b> Current radiographic guidelines suggest unenhanced renal lesions < 20 Hounsfield Units (HU) are overwhelmingly benign, requiring no further evaluation. We evaluate our experience with papillary renal cell carcinoma (pRCC) presenting with low pre-contrast attenuation and the relationship of attenuation with histologic pRCC subtype.<br/>
<b>Materials and methods:</b> We reviewed our institutional kidney cancer database for patients with pT1 or pT2 pRCC between 2003-2017. Tumors were categorized by papillary subtype by expert uropathologists. Preoperative CT images were analyzed at six regional tumor locations. Low, presumably benign, unenhanced median attenuation was defined as ≤ 20 HU. We calculated the frequency of pRCC with low attenuation and assessed the relationship between attenuation and pRCC subtype using logistic regression.<br/>
<b>Results:</b> Sixty-one patients with evaluable imaging were included. Median tumor size was 6 cm (range 1.7 cm to 15.3 cm), with 39% (n = 24) type-1 and 61% (n = 37) type-2. Half of all pRCC tumors (n = 30) exhibited very low pre-contrast attenuation (< 20 HU), risking misdiagnosis as benign using current guidelines. Of these, 80% (n = 24) were type-2 with significant biological potential. Overall, type-2 tumors demonstrated a lower pre-contrast attenuation than type-1 (median HU: 19.8 [range 1.5-42.3] versus 29.6 HU [range 10-45.8], p < 0.01; max HU: 25.3 versus 36.5 HU, p < 0.01). After adjustment, lower pre-contrast HU was an independent predictor of pRCC subtype associated with a 5.5-fold increase of being type-2 (OR = 5.47, p < 0.01).<br/>
<b>Conclusion:</b> pRCCs may exhibit very low attenuation on pre-contrast CT. This appears more common among the more aggressive type-2 subtype. These data suggest that low attenuation (< 20 HU) alone on non-contrast CT imaging is insufficient as a single parameter to rule out malignancy.},
DOI = {}
}