Re: Robotic Partial Nephrectomy in the Treatment of Renal Angiomyolipomas (From: Kara O,Akca O,Zagar H,et al. J Endourol 2016;30:275–279)

Dear Editor:

In the light of our great interest in following up new articles published in the Journal of Endourology, a valuable article attracted our attention in the December issue. Kara and colleagues reported the perioperative and functional outcomes of robotic partial nephrectomy (RPN) in 53 patients with angiomyolipomas (AMLs), and their article appraised the minimally invasive nature of RPN in the treatment of such group of patients, because it is associated with few and low grade complications. Moreover, the renal function was preserved during median follow-up of 7 months. ¹

We reviewed our database for patients with localized renal mass who underwent RPN, and we found 32 patients (10.8%) had AMLs. We retrospectively analyzed the data of those patients. Surprisingly, we found most of our results are in agreement with the Kara and colleagues' report (Table 1). In addition, our study showed a lower rate of postoperative complications (9.3%) and transfusion rate (3.1%) than their study, 15% and 9.4%, respectively.

Unlike in the historical series, we believe that the majority of AMLs are now found incidentally (78.1% of our cases) and hemorrhagic presentation is less common nowadays. We may attribute this to the improvement of the current diagnostic imaging technology, which increases incidence of small renal masses compared with the past.

Intralesional fat on CT and MRI is diagnostic of AMLs; however, the most challenging issue in the diagnosis of AMLs is patients with fat-poor AMLs, because AMLs with minimal fat are difficult to be distinguished from renal-cell carcinoma (RCC) by imaging studies alone. More precise diagnostic strategies have been investigated by radiologists to differentiate fat-poor AMLs from RCC. Recently, Sung and colleagues evaluated the morphologic (i.e., nonround and round appearances, with and without capsule) and enhancement features (i.e., wash-out, gradual, or prolonged) for fat-poor AMLs. They concluded that CT images with nonround shape without the capsule and prolonged enhancements were valuable predictors to differentiate AMLs with minimal fat from RCC. ²

Various treatment options are available for AMLs. Active surveillance (AS) should be offered to asymptomatic AMLs <4 cm. Ouzaid and colleagues reported that AMLs >4 cm and symptoms at initial presentation were highly predictive of discontinuation of AS and intervention. ³ Ablative percutaneous or laparoscopic intervention has shown some promise in treatment of small AMLs; however, we would advocate AS for treatment of such patients. Partial nephrectomy (PN) or selective artery embolization (SAE) is the preferred treatment for symptomatic AMLs >4 cm. We believe that SAE should be used in the context of acute hemorrhage and emergency situations, owing to the high recurrence rate (27%) compared with PN, need of reembolization (18%), increased incidence of postembolization syndrome (63%), and need for lifelong surveillance. ^4,5

Considering Kara and colleagues' study, which is supported by our results, RPN in the treatment of AMLs seems to offer a wide safety profile, no recurrence after surgery, and good functional outcomes, in addition to being a minimally invasive procedure. We agree with their conclusion that RPN should be offered as a reliable treatment option for symptomatic AMLs >4 cm.