Abstract: PD11-06
Sources of Funding: None

Introduction

We evaluate intervention rates and survival outcomes of complex renal cysts in a single center experience. Outcomes stratified by initial classification according to the Bosniak classification system.

Methods

We used a radiology data-mining system (Montage; Montage Healthcare Systems, Philadelphia, PA, USA) to retrospectively review the radiology database in an academic health center between 2001 and 2013 to identify all cases of "complex cyst." Primary end points were overall (OS) and cancer specific survival (CSS).

Results

248 patients were identified using the Montage system to have radiographic reports of complex renal cysts. Of these, 141 (56.9%), 86 (34.7%), and 21 (8.4%) had Bosniak 2F, 3 and 4 cysts, respectively. Median follow-up was 66.05±54.24 months with an average of 3.61 scans (all modalities) per year. Of the 244 patients for whom we had follow-up, there were no cancer-specific deaths and overall mortality was 7.4%. Only 1 patient (4.7%) with a Bosniak 4 lesion at diagnosis developed metastases during follow-up. 20 patients underwent percutaneous biopsy of a solid nodule within the cyst; 7 (35%) were found to have renal cell carcinoma, and all of these patients received treatment. With regards to intervention, 6 (4.3%), 31 (36.0%) and 13 (61.9%) of the Bosniak 2F, 3 and 4 patients underwent either surgical or ablative intervention, respectively. Indication for intervention was predominantly age (median age: intervention 50.3±14.6, no intervention 63.4±13.3). Median time to intervention from initial identification was 6.45 months. Extirpative surgery with radical (17 patients, 34%) or partial nephrectomy (30 patients, 60%) was the predominant intervention, while 3 patients (6%) underwent ablation. While 4 patients (8.5%) had benign final pathology, the remainder had RCC: 23 (48.9%) clear cell RCC, 10 (21.2%) multilocular cystic RCC, 7 (14.9%) papillary type 1 RCC, 3 (6.4%) papillary type II RCC and 1 (2.1%) tubulocystic RCC. The majority (95.1%) were Fuhrman grade 1 or 2; 2 patients (4.9%) were Fuhrman grade 3. None of the patients undergoing intervention had evidence of recurrence during follow-up. Even when excluding patients undergoing intervention, CSS remained 100%.

Conclusions

Cancer-specific survival and overall survival for patients diagnosed with Bosniak 2F-4 complex renal cysts remains quite high; there were no cancer-specific deaths, even in the group that received no intervention. Reconsideration of management guidelines for complex renal cysts based on Bosniak classification system is warranted, particularly for Bosniak 3 cysts.

Funding

None