Management, pathology and outcomes of Bosniak category IIF and III cystic renal lesions

To analyze the management, pathology and outcomes of Bosniak category IIF and III cystic renal lesions.

This retrospective study included 85 consecutive patients with Bosniak category IIF and III lesions, who were actively surveilled or surgically treated at three academic urology centers between 2003 and 2012. Outcomes of interest included the rates of cyst progression and pathology.

Overall, 27 patients with Bosniak category IIF lesions were initially managed by active surveillance, from which eighteen (67 %) did not progress after a median interval of 64 months, while 9 (33 %) underwent surgery within a median interval of 18 months. There were 58 patients with Bosniak category III lesions, 54 (93 %) of which were managed by surgery. Compared with Bosniak category IIF, Bosniak category III lesions had more frequently proven RCC (64 vs. 30 %, p = 0.005). Of the tumors that underwent surgical extirpation, the T stage, grade (p = 0.65) and subtype distribution (p = 0.36) did not differ between the Bosniak categories. The majority of RCCs were low-stage and low-grade tumors. One patient developed a local recurrence. There were no RCC-specific deaths.

As only a minority of Bosniak IIF lesions are malignant and the majority are low-stage and low-grade tumors, initial active surveillance is the standard of care for these lesions. Progressive Bosniak IIF lesions may undergo later RCC treatment without seemingly loosing the window of cure. Bosniak III lesions harbor a high risk of malignancy and should be managed as solid renal tumors according to contemporary guidelines.