Huge schwannoma arising from the renal sinus: A case report with imaging and literature review

Renal sinus schwannomas are extremely rare. In this study, we inform a case of a large schwannoma that was suspected to have originated in the renal sinus based on preoperative imaging. A male in his 40s was referred to our hospital due to the incidental detection of a large tumor in his right kidney was during an abdominal CT scan performed to discover the underlying cause of decreased renal function. The tumor was a well-circumscribed mass, 17 cm in diameter, and contained large cystic degeneration. The contrast-enhanced CT revealed that the tumor was pressing on the normal structures of the renal parenchyma, renal pelvis, and renal artery. MRI was taken. The solid part of the tumor showed a uniform slightly high signal on T2-weighted image. Consequently, nephrectomy was performed. On pathological examination, the tumor was schwannoma originated in the renal sinus. If a huge well-circumscribed tumor is found in the renal sinus, a schwannoma should be listed in the differential.