Clinical Features

The patient with orbital hemangiopericytoma develops a slowly progressive unilateral proptosis with or without pain and visual acuity decrease. Pain was present in 21 to 29% of the patients in two series.57,59 The majority of these tumors occur superiorly in the orbit and produce downward displacement of the globe (Figure 14.12).56,57 However, rarely the tumor can occupy the inferior orbit.60 There may be intermittent upper eyelid swelling resembling angioneurotic edema.56 Sometimes the skin overlying the tumor is bluish.56,58 Other manifestations of a space-occupying orbital mass that may occur with hemangiopericy-toma include ocular motility problems, visual field loss, afferent pupillary defect, optic disk edema, and choroidal folds.57

The slow growth rate of hemangiopericytoma is evident by the long duration of symptoms reported by many patients.56,58 However, malignant hemangio-pericytomas can also demonstrate rapid growth, spanning a few months. In one such case the production of conjunctival chemosis was reported.61

FIGURE 14.12. (A,B) Axial CT and sagittal Tl-weighted MR images show a well-delineated vascular tumor within intra- and extraconal space. (C) Histopathologically, the tumor was composed of proliferation of spindle-shaped pericytes with a low mitotic rate; photomicrograph reveals the ultrastructural appearance of a neoplastic pericyte with a rounded nucleus (N) and irregular deposits of basement membrane material (white arrows) in the intercellular matrix between neoplastic cells (C). (D) Immunohistochemical preparation that is markedly CD34 positive (brownish staining).

There have been reports of choroidal,62 lacrimal sac,63 and optic nerve64 involvement by hemangiopericytoma.

Hemangiopericytoma may take a malignant clinical course (Figure 14.13). Malignant hemangiopericytomas tend to undergo local recurrence, invasion into the central nervous system, and metastasis to distant organs, particularly the lungs, bone, and liver. A rare case of hemangiopericytoma metastatic to the breast has also been reported. The biologic behavior of this tumor cannot be predicted from the histopathologic appearance of the lesion.59 A tumor with benign histopathologic features can demonstrate malignant clinical behavior.

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