Hemangiopericytoma of the lacrimal sac.

Hemangiopericytomas of the orbit are rare tumors with low malignancy potential. To the authors' knowledge, only three previous cases of these tumors occurring in the lacrimal sac have been reported. The authors report a fourth case. Follow-up was obtained on the first reported case, and the patient in that case had a recurrence after 15 years. These tumors should be totally excised and followed for long periods of time.