Follow-up for Bosniak category 2F cystic renal lesions.
OBJECTIVE
To determine percentage of Bosniak category 2F complex cystic renal masses that progress to malignancy based on serial follow-up studies,and to determine if there are demographic and/or imaging features associated with progression.


METHODS
This retrospective study was institutional review board-approved with waiver of informed consent. Hospital database system was searched from January 1, 1996, to May 1, 2011, for category 2F cysts studied with contrast agent-enhanced computed tomography or magnetic resonance imaging and followed with serial contrast-enhanced imaging. Demographics of patients and imaging features of lesions that progressed were compared with those that did not. The relationship of these features to progression or stability was assessed by using χ(2), Fisher exact, or Cochran Armitage trend tests.


RESULTS
Identified in 144 patients (98 men, 46 women; age range, 31-83 years; average, 63 years) were 156 category 2F lesions. Follow-up studies were from 6 months to 13 years (median, 3.6 years; average, 4.2 years). Nineteen of 156 lesions progressed to category 3 or 4 in 6 months to 3.2 years; 17 lesions (89.5% of those that progressed and 10.9% of initial 2F lesions) were malignant and two were benign. To date, no patients had recurrent or metastatic disease. Men had significant risk for progression to malignancy (P = .003). Of 17 category 2F lesions that progressed to malignancy, 12 were endophytic (P = .02). Category 2F lesions with minimally irregular septa (nine of 17; P= .001) or wall (seven of 17; P = .016), and lesions with indistinct parenchymal interface (nine of 17; P < .001) were associated with progression to cancer. A multilobulated border was not associated with progression (P = .999).


CONCLUSIONS
Based on this study, 10.9% (17 of 156) Bosniak category 2F cystic lesions progress to malignancy, and progression occurs within 6 months to 3.2 years.
From the Department of Radiology, NYU School of Medicine, 550 1st Ave, HW 202, New York, NY 10016 (N.M.H., M.A.B.); and Department of Radiology, Columbia University, New York, NY (E.M.H.).
Nicole M
NM
Hindman
Elizabeth M
EM
Hecht
Morton A
MA
Bosniak
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D052177:Kidney Diseases, Cystic / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed / Q000379:methods*