Orbital hemangiopericytomas: A clinical and pathologic study of five cases

Hemangiopericytomas are rare vascular tumors arising from Zimmerman's pericytes, which ubiquitously surround blood capillaries and post-capillary venules. The orbit is an uncommon site; mostly isolated cases or small series are reported; the authors' series includes five cases (two males and three females, mean age 40 years, range 21-79 years). The tumors were rarely painful and were usually noticed because of a rapid growth; in three cases there was evidence of recurrence after surgical excision. Up to today the follow-up time ranges between one and 22 years. Histopathologic and immunohistochemical data are also reported with particular attention to the differential diagnosis. The authors also try to correlate the anatomopathological features with the clinical behavior.