Clinicopathological characteristics and typing of multilocular cystic renal neoplasm of low malignant potential

Background: Up until now, no research has been reported on the association between the clinical growth rate of multilocular cystic renal neoplasm of low malignant potential (MCRNLMP) and computed tomography (CT) imaging characteristics. Our study sought to examine the correlation between them, with the objective of distinguishing unique features of MCRNLMP from renal cysts and exploring effective management strategies.

Aim: To investigate optimal management strategies of MCRNLMP.

Methods: We retrospectively collected and analyzed data from 1520 patients, comprising 1444 with renal cysts and 76 with MCRNLMP, who underwent renal cyst decompression, radical nephrectomy, or nephron-sparing surgery for renal cystic disease between January 2013 and December 2021 at our institution. Detection of MCRNLMP utilized the Bosniak classification for imaging and the 2016 World Health Organization criteria for clinical pathology.

Results: Our meticulous exploration has revealed compelling findings on the occurrence of MCRNLMP. Precisely, it comprises 1.48% of all cases involving simple renal cysts, 5.26% of those with complex renal cysts, and a noteworthy 12.11% of renal tumors coexisting with renal cysts, indicating a statistically significant difference (P = 0.001). Moreover, MCRNLMP constituted a significant 22.37% of the patient population whose cysts demonstrated a rapid growth rate of ≥ 2.0 cm/year, whereas it only represented 0.66% among those with a growth rate below 2.0 cm/year. Of the 76 MCRNLMP cases studied, none of the nine patients who underwent subsequent nephron-sparing surgery or radical nephrectomy following renal cyst decompression experienced recurrence or metastasis. In the remaining 67 patients, who were actively monitored over a 3-year postoperative period, only one showed suspicious recurrence on CT scans.

Conclusion: MCRNLMP can be tentatively identified and categorized into three types based on CT scanning and growth rate indicators. In treating MCRNLMP, partial nephrectomy is preferred, while radical nephrectomy should be minimized. After surgery, active monitoring is advisable to prevent unnecessary nephrectomy.