[Retroperitoneal hemangiopericytoma-a rare case with multiple relapses-even 20 years after primary diagnosis].

A 41-year-old man without previous illness presented at our clinic with progressive pain in the lower abdomen and intermittent pain in the left flank. We found a lesion of unknown dignity which had anatomical contact to the bladder and rectum. Histological examination confirmed the diagnosis of hemangiopericytoma. It is grouped under the general term solitary fibrous tumor (SFT). The potential for malignancy varies. To calculate the tendency of metastases or recurrence and overall survival, it is necessary to use a risk stratification model to individualize treatment. Our rare case with an appearance of a relapse 14 and 20 years after the primary resection and progressive proliferation rate underlines the importance of individualized management and long-term and close follow-up of this tumor entity.