Solitary Fibrous Tumor in the Retroperitoneal Space Arising from the Diaphragm

We present a case of solitary fibrous tumor, arising from the diaphragm in the retroperitoneal space, that was resected with robotic assistance.

An 85-year-old female patient was referred to our hospital for evaluation of a suspected right renal tumor. Abdominal contrast-enhanced computed tomography revealed a tumor (maximum diameter, 36 mm) protruding from the superior pole of the right kidney. The patient was scheduled for robot-assisted, retroperitoneoscopic, partial nephrectomy based on a preoperative diagnosis of renal cell carcinoma. Intraoperative findings revealed that the tumor originated from the diaphragm and had no continuity with the renal parenchyma. Pathological examination revealed a solitary fibrous tumor.

Solitary fibrous tumors are rare soft-tissue neoplasms with a distinct molecular feature of the fusion of nerve growth factor-inducible A gene-binding protein 2 with signal transducer and activator of transcription 6 gene (NAB2::STAT6). We believe that this is the first reported case of a solitary fibrous tumor arising from the diaphragm in the retroperitoneal space.