Malignant/Sarcomatous Transformation of Mixed Epithelial and Stromal Tumor of the Kidney: A Case Report.

INTRODUCTION

Malignant transformation of mixed epithelial and stromal tumors of the kidney (MESTK) is extremely rare.

CASE PRESENTATION: A 39-year-old man with gross hematuria was suspected to have renal cell carcinoma, measuring 13 cm in diameter. No distant metastases were observed. The patient underwent laparoscopic left nephrectomy. Histopathological examination revealed malignant sarcomatous transformation of MESTK. Immunohistochemically, the tumor was positive for PAX8, CD10, and desmin, as well as for estrogen, progesterone, and androgen receptors. Comprehensive genomic profiling did not yield any treatment recommendations or relevant information. The patient will be closely monitored for any signs of recurrence or metastasis.

CONCLUSION

The associated prognosis for patients with nonmetastatic MESTKs exhibiting malignant transformation is unknown; however, strict follow-up is recommended due to the histological grade of malignancy and local invasion.