CASE REPORT

A 71 year old woman noted a photopsia, diplopia, and peripheral scotoma in her left eye. She was evaluated and underwent laser treatment for suspected retinal hole at the margin of a presumed retinal detachment. After non-resolution of the “detachment”, a second ophthalmologist raised the possibility that the fundus lesion was a choroidal melanoma. The patient was then referred to the oncology service for further management. Ocular examination revealed corrected visual acuity of 6/7.5 in both eyes. Proptosis of 3 mm with minimal limitation of supraduction and infraduction was noted. Fundus examination showed an elevated choroidal mass with normal appearing retinal and choroidal vessels overlying the mass. The mass did not shift with eye position. Fluorescein angiography demonstrated retinal and choroidal isofluorescence in the area of the mass (Fig 1). B-scan ultrasonography showed an echolucent mass compressing the sclera, measuring 16×16×12 mm. Based on these findings, an orbital tumour producing globe compression was suspected.

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Figure 1

Late venous phase of fluorescein angiography showing retinal and choroidal isofluorescence.

Magnetic resonance imaging was performed to more clearly delineate the soft tissue mass. A well circumscribed intraconal mass was found adjacent to the sclera inferomedially, producing globe compression and inferior rectus displacement (Fig 2). On T1 weighted images, the lesion was isointense and on T2 weighted images, hyperintense with respect to muscles. Marked enhancement of the lesion with gadolinium was found. Our differential diagnosis included orbital cavernous haemangioma, neurofibroma, schwannoma, fibrous histiocytoma, and haemangiopericytoma.

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Figure 2

Coronal T1 weighted magnetic resonance image demonstrating intraconal orbital mass compressing the globe.

The patient underwent transconjunctival excisional biopsy. The pink encapsulated mass was composed of spindle cells with moderate mitotic activity. Staghorn vascular channels were evident, and in several areas the tumour cells invaded the pseudocapsule.

The histopathological diagnosis was benign haemangiopericytoma. The patient has been followed for 1 year without further problems.

COMMENT

Haemangiopericytoma is a rare vascular tumour derived from an abnormal proliferation of pericytes. It rarely occurs in the orbit, accounting for only 1% of all orbital biopsies.1-5 Orbital haemangiopericytoma occurs as a painless, unifocal tumour often in the muscle cone.1-5 The majority of cases are recognised between the ages of 20–70 years.1-5 In most cases there is progressive proptosis. However, in our case mild proptosis but marked compression of the globe was seen. Orbital haemangiopericytoma poses a risk for recurrence and metastasis, especially when the tumour invades beyond the pseudocapsule.3-5

Orbital haemangiopericytoma generally is a slow growing tumour that has an ocular and systemic prognosis.1-5 There is a risk for recurrence and metastasis when the pseudocapsule is breached.4 In one series, a 30% recurrence rate was noted with recurrences generally occurring 1 month to 7 years after surgery.3 Our patient may be at risk of developing orbital recurrence in the future because there was invasion of the pseudocapsule.

Orbital tumours should be included in the differential diagnosis of a solid intraocular mass. Those orbital tumours that arise in the muscle cone adjacent to the sclera may produce these confusing clinical features.