Primary Renal Myoepithelial Carcinoma with EWSR-1 Gene Rearrangement-Case Report and Literature Review

Myoepithelial neoplasms are a group of rare, locally aggressive malignant tumors that originated from the salivary gland, soft tissue, or skin. Primary renal involvement has been seldom reported. The diagnosis and effective treatment remain challenging because of high spectrum of morphological and cytological diversity. The presence of Ewing sarcoma breakpoint region 1 (EWSR1) gene rearrangement may help for molecular diagnosis of this entity; however, the prognostic significance of this gene defect remains elusive. We reported a 19-year-old girl presented with abdominal pain secondary to huge cystic renal tumor bleeding. A diagnosis of primary myoepithelial carcinoma of the kidney with EWSR1 gene rearrangement with complete loss of integrase interactor-1 and diffuse metastasis was made. Cytoreduction surgery and trials of chemotherapy consisted of combinations of vincristine/cyclophosphamide/doxorubicin, mitoxantrone, 5-fluorouracil, tazemetostat, paclitaxel/gemcitabine, and bevacizumab/ifosfamide/etoposide can achieve the survival of 39 months. A review of cases of primary myoepithelial carcinoma of kidney was also summarized in this report.