Cystic renal oncocytoma mimicking renal cell carcinoma

Abstract

Cystic renal lesions are one of the commonly encountered urological conditions. They can be either benign or malignant. The Bosniak classification is employed to differentiate benign cysts from the malignant ones and to recommend treatment options. Bosniak type 4 cysts are mostly malignant. Rarely, benign tumors can be encountered in Bosniak type 4 cysts. We present a 59-year-old female who presented with a hilar Bosniak type 4 cyst in the right kidney. She underwent open exploration of the right renal tumor. The tumor was infiltrating into the renal vessels and could not be separated from the renal vein. In view of preoperative and intraoperative suspicion of malignancy, radical nephrectomy was done. Postoperative histopathological examination revealed the tumor to be an oncocytoma. The benign nature of the cyst could not be conclusively determined by preoperative investigations and intraoperative findings. Postoperative histological examination uncovered the rare cystic presentation of this benign tumor.

CEUS Bosniak Classification—Time for Differentiation and Change in Renal Cyst Surveillance

“…The benign renal neoplastic cystic lesions include cystic nephroma, mixed epithelial and stromal tumor, cystic renal oncocytoma, angiomyolipoma with epithelial cysts, lymphangioma, angiomyolipoma with epithelial cysts, and cystic partially differentiated nephroblastoma [6,11,15,16]. In cystic nephroma, mixed epithelial and stromal tumor, and cystic renal oncocytoma, malignant transformation has been reported [16,17], whereas to date, no malignant transformation has been described in the other entities. However, due to the rarity of these types of cysts, the data are limited [16,18,19].…”

“…However, due to the rarity of these types of cysts, the data are limited [16,18,19]. The characteristics of these lesions have been explained and summarized in several studies [6,11,[15][16][17][18][19].…”

Molecular Characterization of Metastatic Oncocytoma With Exceptional Response to Treatment: A Case Report

“…Renal oncocytoma (RO) is a neoplasm originating from tubular intercalated cells and is typically considered a benign lesion. 1,2 Classically, ROs present as a solid, unilateral mahogany-colored mass with a central scar, with bilateral occurrence in approximately 5% of cases. 1,2 Histologically, ROs contain eosinophilic cells with low-mitotic activity.…”

“…1,2 Classically, ROs present as a solid, unilateral mahogany-colored mass with a central scar, with bilateral occurrence in approximately 5% of cases. 1,2 Histologically, ROs contain eosinophilic cells with low-mitotic activity. RO diagnosis can be challenging because of overlap with other tumors like chromophobe renal cell carcinoma (chRCC) or hybrid oncocytomas.…”