Multilocular Cystic Renal Cell Neoplasm of Low Malignant Potential: A Series of 76 Cases

Multilocular cystic renal cell carcinoma (MCRCC) is a rare and distinct subtype of clear cell renal cell carcinoma (RCC). The incidence of MCRCC in patients with RCC is low. MCRCC has distinct pathologic features, and its nuclear grade is unrelated to the tumor size and TNM stage. Thus, the follow-up interval after surgery can be longer to minimize unnecessary examinations. Introduction: Multilocular cystic clear cell renal cell neoplasm of low malignant potential or multilocular cystic renal cell carcinoma (MCRCC) is a rare distinct subtype of clear cell renal cell carcinoma (RCC). No large series of cases have been reported to date. The present study aimed to characterize the clinical and pathologic features of MCRCC. Patients and Methods: From January 2006 to December 2014, 76 cases were identified as MCRCC among 4345 patients with RCC at our institution. Their clinical and characteristics, surgical management, pathologic features, and outcomes were retrospectively reviewed. Results: The incidence of MCRCC in our patients with RCC was 1.7%. The mean age at diagnosis was 46.7 +/- 10.5 years (range, 18 to 80 years). Most cases showed no symptoms. Nuclear grade was unrelated to the tumor size (P=.112) and TNM stage (P=.451). Of these 76 patients, 66 (86.8%) were followed up for a median of 52 months, and no tumor recurrence or metastasis was found. Conclusion: The incidence of MCRCC in patients with RCC is low. The nuclear grade of MCRCC cases was unrelated to the tumor size and TNM stage, suggesting that the current stage criteria might not suitable for this lesion. Patients with MCRCC have an excellent prognosis; thus, the follow-up interval after surgery can be longer to minimize unnecessary examinations. (C) 2016 Elsevier Inc. All rights reserved.