Spindle cell/pleomorphic lipoma of the seminal vesicle: First description of a rare benign mesenchymal tumor.

We describe the first case of a spindle cell/pleomorphic lipoma of the seminal vesicle. A 6.2cm large mass originating from the left seminal vesicle was incidentally detected on imaging for peripheral arterial disease. A transrectal ultrasound-guided biopsy was negative for malignancy. We proceeded with a robotic tumor resection due to the size of the mass and sarcomatoid features present on MR imaging. The final pathological work-up revealed a spindle cell/pleomorphic lipoma, immunohistochemical staining was performed with no malignant features detected, in particular no signs of an atypical lipomatous tumor. Ejaculatory function was preserved with reduced volume at 6-weeks follow-up.