Mixed epithelial and stromal tumor of the kidney with prominent peritumoral adipose tissue: a case report radiologically mimicking angiomyolipoma with epithelial cysts
- 1The First Clinical Medical College of Guizhou University of Traditional Chinese Medicine , ,
- 2Department of Urology & Andrology, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine , ,
Abstract
Mixed epithelial and stromal tumor of the kidney (MEST) is a rare renal neoplasm with biphasic differentiation comprising epithelial and stromal components. It typically appears as a mixed cystic-solid mass on imaging, and the prognosis is favorable in the vast majority of cases. We report a case of MEST with a prominent fat component on imaging: a 54-year-old woman was admitted with a 1-month history of left flank distension and pain. Contrast-enhanced computed tomography (CT) showed a mixed cystic-solid mass at the lower pole of the left kidney, with a prominent low-attenuation fat-density area surrounding the mass. Preoperatively, the lesion was considered an unusual angiomyolipoma with epithelial cysts (AMLEC). Because the lesion was small, located at the lower pole, and relatively well circumscribed, the patient underwent laparoscopic left partial nephrectomy. Postoperative histopathologic examination confirmed that the left renal mass was benign; however, immunohistochemistry (IHC) demonstrated positivity for EMA and PCK in the epithelial component and for PR and ER in the stromal component, supporting a diagnosis of MEST. The adipose tissue submitted separately with the tumor was located around the tumor and could not be definitively confirmed as an intratumoral component. This case demonstrates that MEST may also exhibit prominent adipose tissue on imaging and illustrates the diagnostic pitfall in which fat-related imaging findings cause MEST to mimic AMLEC, making the early distinction between MEST and cystic change in fat-containing renal tumors challenging.
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BibTeX
@article{wu2026mixed,
title = {{Mixed epithelial and stromal tumor of the kidney with prominent peritumoral adipose tissue: a case report radiologically mimicking angiomyolipoma with epithelial cysts}},
author = {Chuanchuan Wu and Yang Zhang and Bangwei Che and Jiancheng Zhai and Shenglan Yuan and Linjie Lu and Kai Xiong and Yinqian Li and Kai-Fa Tang},
journal = {Frontiers in oncology},
year = {2026},
month = oct,
doi = {10.3389/fonc.2026.1918612},
url = {https://europepmc.org/article/PMC/PMC13671961},
note = {CC BY},
}
RIS
TY - JOUR
TI - Mixed epithelial and stromal tumor of the kidney with prominent peritumoral adipose tissue: a case report radiologically mimicking angiomyolipoma with epithelial cysts
AU - Chuanchuan Wu
AU - Yang Zhang
AU - Bangwei Che
AU - Jiancheng Zhai
AU - Shenglan Yuan
AU - Linjie Lu
AU - Kai Xiong
AU - Yinqian Li
AU - Kai-Fa Tang
PY - 2026
DA - 2026/10/02
JO - Frontiers in oncology
DO - 10.3389/fonc.2026.1918612
UR - https://europepmc.org/article/PMC/PMC13671961
AB - Mixed epithelial and stromal tumor of the kidney (MEST) is a rare renal neoplasm with biphasic differentiation comprising epithelial and stromal components. It typically appears as a mixed cystic-solid mass on imaging, and the prognosis is favorable in the vast majority of cases. We report a case of MEST with a prominent fat component on imaging: a 54-year-old woman was admitted with a 1-month history of left flank distension and pain. Contrast-enhanced computed tomography (CT) showed a mixed cystic-solid mass at the lower pole of the left kidney, with a prominent low-attenuation fat-density area surrounding the mass. Preoperatively, the lesion was considered an unusual angiomyolipoma with epithelial cysts (AMLEC). Because the lesion was small, located at the lower pole, and relatively well circumscribed, the patient underwent laparoscopic left partial nephrectomy. Postoperative histopathologic examination confirmed that the left renal mass was benign; however, immunohistochemistry (IHC) demonstrated positivity for EMA and PCK in the epithelial component and for PR and ER in the stromal component, supporting a diagnosis of MEST. The adipose tissue submitted separately with the tumor was located around the tumor and could not be definitively confirmed as an intratumoral component. This case demonstrates that MEST may also exhibit prominent adipose tissue on imaging and illustrates the diagnostic pitfall in which fat-related imaging findings cause MEST to mimic AMLEC, making the early distinction between MEST and cystic change in fat-containing renal tumors challenging.
SN - 2234-943X
ER -