[A rare tumour: paravesical pelvic haemangiopericytoma (author's transl)].

Haemangiopericytomas are vascular tumours derived from Zimmerman's pericytes, the cells surrounding blood capillaries which correspond to the smooth muscle cells in the arterial and venous walls. This rarely observed tumour is usually found in the limbs (more than 50 p. cent of cases) or the face. Pelvic haemangiopericytomas are most frequently observed in women, and are then of uterine origin, their occurrence in men, and in the perivesical space, being exceptionally rare (seven cases reported in the publishing literature). The authors describe such a case, and review the clinical and radiological characteristics of the lesion. Diagnostic difficulties are emphasized, as confusion with a sarcoma can arise, even after histological examination. Surgical excision should be conducted routinely, but local recurrence or pulmonary metastases may occur in view of the potential malignancy of these tumours. Complementary cobalt therapy is therefore justified.