Nicole Maria Hindman MD, Presenter: Nothing to Disclose

Elizabeth M. Hecht MD, Abstract Co-Author: Nothing to Disclose

Morton Arthur Bosniak MD, Abstract Co-Author: Nothing to Disclose

To evaluate the natural history of Bosniak 2F cystic renal masses based on serial long term follow up and propose a length of follow up for these lesions.

A rad database was searched from 1/1/96 - 5/1/11 for all 2F lesions with C+ CT or MR and at least 6 mo f/u with C+ CT or MR. 214-2F lesions fulfilled these criteria. All lesions were independently reviewed by 2 radiologists and classified as 2F or re-classified as Cat. 2 (benign) or 3 (probably malignant). A third senior radiologist reviewed any case where there was disagreement. Lesions were excluded if 2 of the 3 radiologists upgraded to Cat 3 (6/214) or downgraded to Cat 2 (52/214): this yielded 156 2F cases. All 2F lesions had f/u studies ranging from 6 mos to 13 yrs (median-4 yrs, avg 4.6 yrs). Imaging features of the lesions that progressed were compared to those that remained stable. The relationship of these features to progression or stability was assessed using Chi-Square, Fisher’s exact, or Cochran Armitage trend tests.

156-2F lesions were identified in 144 pts: 98 M:46 F; avg age 63.6 yrs. Kappa between the 2 readers for imaging features (before expert final read) ranged from 0.856-1.000, avg 0.943. Of the 156 lesions, 19 progressed to Cat 3 or 4 on f/u (3 mos-3 yrs, avg 18.1 mos). 17/19 progressed lesions represented renal neoplasms; 2 were benign. 0/19 pts that progressed had recurrent or metastatic disease (follow-up 1-10 yrs, avg 3.4 yrs). Male sex, age < 60 yrs & h/o prior renal cancer favored progression, but this did not reach stat. significance (p values of 0.09, 0.08 and 0.07). Presence of hemorrhage (p=0.04) was predictive of progression. Imaging modality did not correlate with upgrading of a lesion (p =0.078). Of the Cat 2F lesions that had stable imaging features at 1 yr, 10% progressed on f/u. Initial cyst size and change in lesion size did not correlate with progression (p=0.843, p=0.188), but irregular thickness of septae/wall did (p=0.005 and p=0.007).

Based on our institution’s experience and long term follow up of the largest series of Cat 2F lesions to date, we propose that 2F lesions should be followed for 3-5 yrs. For those lesions that are stable or downgraded within this time-frame, no further follow-up imaging seems necessary.

Bosniak 2F lesions should be followed for 3-5 years; if stable or downgraded after that period of time, data would suggest, no further follow-up imaging is necessary.

Hindman, N, Hecht, E, Bosniak, M, Long Term Follow-up of Bosniak 2F Cystic Renal Lesions.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12023664.html