腎臟同時表現混合性上皮和間質瘤與血管平滑肌脂肪瘤之罕見案例報告

孫浩議¹、薛又仁²、黃建榮²、賴昱維²、蕭毅君²、李淑文²、高國維²、陳修聖²、邱文祥²

¹臺北市立聯合醫院忠孝院區外科部泌尿科

²臺北市立聯合醫院仁愛院區外科部泌尿科

A Case Report: Concomitant Presentation of Mixed Epithelial and Stromal Tumor with Angiomyolipoma in the Kidney

Hao-Yi Sun ¹, Thomas Y. Hsueh ², Andy C. Huang ², Yu-Wei Lai ², Yi-Chun Hsiao ², Shu-Wen Li ²,
Kuo-Wei Kao ², Shiou-Sheng Chen ², Allen W. Chiu ²

¹ Division of Urology, Department of Surgery, Zhongxiao Branch, Taipei City Hospital

² Division of Urology, Department of Surgery, Renai Branch, Taipei City Hospital

Introduction

Mixed Epithelial and Stromal Tumor (MEST) of the kidney represents a unique and uncommon neoplasm, characterized by its variable cystic and solid components that exhibit morphologically diverse epithelial and stromal elements. Representing about 0.2% of all renal tumors, MEST typically affects perimenopausal women, often those with a history of long-term hormonal treatment, showcasing a significant gender disparity with a female to male ratio of 10:1. The mean age of presentation is around 52 years. Symptoms are frequently nonspecific, with many cases discovered incidentally, although abdominal or flank pain, hematuria, and urinary tract infections can occur. These tumors are generally solitary, well circumscribed, presenting a mix of solid and cystic areas upon gross examination. Treatment predominantly involves surgical intervention, ranging from nephron-sparing surgery to radical nephrectomy. We presented a 58-year-old female with concomitant occurrence of mixed epithelial and stromal tumor alongside angiomyolipoma in the kidney.

Case presentation

A 58-year-old female with a history of stage 3 sigmoid cancer treated in 2016 was found to have a coincidental right renal tumor. Over the years, the patient experienced an increase in symptoms including tea-colored urine and elevated blood pressure, leading to the decision for a laparoscopic right radical nephrectomy in 2023. History of hormone supplements was denied. Pre-operative assessments revealed a mixed epithelial and stromal tumor alongside an angiomyolipoma within the right kidney, with no evidence of acute obstructive uropathy or malignancy with bone metastasis from imaging and functional studies. Pathology confirmed the presence of a 5.3x4.1x3.1 cm MEST and a 1.5x1.4x1.0 cm angiomyolipoma (AML). Immunohistochemical results distinguished the two lesions. The large tumor was positive for calponin, desmin, estrogen and CD10. Progesterone receptor was focally positive. Melan-A, HMB-45, and Mart were negative. The positive rate of Ki-67 was less than 1%. Postoperative course was smooth.

Conclusion

The rarity of MEST itself, a complex and uncommon neoplasm characterized by its diverse morphological features, underscores the uniqueness of this case.  To our knowledge, this was the first documented instance worldwide of a concomitant presentation of MEST and AML. Despite being mostly benign, rare instances of local recurrence, aggressive behavior, and malignant transformation have been documented.