Retrorectal hemangiopericytoma: a case report.

Hemangiopericytoma is a rare, vascular soft tissue tumour originating from the pericytes, the contractile cells that surround capillaries. A case of retrorectal hemangiopericytoma in a 49-year-old woman is reported. With a posterior sagittal approach, the tumour was completely removed. Pathological examination, including immunohistological stains, was consistent with a hemangiopericytoma. A step-by-step approach to a retrorectal tumour is exemplified, and a very rare pathological entity is added to the spectrum of retrorectal masses.