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A novel ETV6-NTRK3 gene fusion in primary renal fibrosarcoma.

INTRODUCTION
Primary renal fibrosarcoma is a relatively uncommon tumor in the urinary system of adults, in fact only 6 cases have been reported in the English literature so far worldwide. The etiology of renal fibrosarcoma is incompletely understood. It is still lacking in simple and specific tissue-based biomarkers to assist the diagnosis of renal fibrosarcoma. Among the previously reported cases in the literature, the ETV6-NTRK3 gene fusion could be detected in the congenital (or infantile) fibrosarcoma, and this rearrangement may play a vital role in initiation of congenital fibrosarcoma. However, the ETV6-NTRK3 expression has not been reported in adult-type fibrosarcoma in the literature so far.


CASE PRESENTATION
A 66-year-old male patient admitted to our hospital because of chills, fever, and a right indwelling percutaneous nephrostomy catheter. Compared to normal kidney, the right renal had a thinner cortex and no function. After a week of anti-infective treatment, the patient underwent retroperitoneal laparoscopic right nephrectomy. The postoperative pathological result was fibrosarcoma of the right kidney.


CONCLUSIONS
Aberrant expression of EVT6-NTRK3 may contribute to the development of renal fibrosarcoma.