|Ahead of print publication
Orbital hemangiopericytoma in teens: A rare case
Mohammad Javed Ali, Santosh G Honavar, Milind N Naik, Geeta K Vemuganti
Ocular Oncology Service, L. V. Prasad Eye Institute, Road No 2, Banjara Hills, Hyderabad - 500034, India
|Date of Submission||11-May-2011|
Santosh G Honavar,
Ocular Oncology Service, L. V. Prasad Eye Institute, Road No 2, Banjara Hills, Hyderabad - 500 034
Source of Support: None, Conflict of Interest: None
Orbital hemangiopericytomas are rare tumors which frequently affect adults. Nearly 80% of the patients are above 20 years of age. They are characterized by a spectrum of pericyte proliferation, poses surgical difficulties because of its highly vascular nature with possible local infiltration and unpredictable spectrum of aggressiveness. We describe a teenage patient with an orbital hemagiopericytoma which was completely excised.
Keywords: CD 31, CD 34, hemangioperictyoma, orbits, solitary fibrous tumor
Hemangioperictyomas are uncommon tumors which infrequently occur in the head and neck in adults. Orbital hemangiopericytomas are rare tumors with the incidence ranging from 1% to 1.5% in very large orbital series. , They most frequently occur in adults with nearly 80% of the patients being 20-70 years of age.  The median age of occurrence is in the fourth decade.  The diagnosis of hemangiopericytoma cannot be made with certainty on clinical or radiological evaluation and requires histologic confirmation. The origin from the vascular pericytes have been recently questioned and the tumor has been reclassified as solitary fibrous tumor, based on histopathologic and immunohistochemical observations. ,, We describe a rare case of hemangiopericytoma in a teenager with radiologic, histopathologic and immunohistochemistry correlation.
| Case Report|| |
A 17-year-old girl presented with swelling of the right upper lid since the past 2 years and painless downward displacement of the eyeball since the past 1 year unassociated with visual symptoms. Physical examination showed periocular fullness more so in the subbrow region with a 1 mm of proptosis and 3 mm downward displacement of the eyeball [Figure 1]. The visual acuity was 20/20 and the fundus examination was normal in both the eyes. Ocular movements were normal other than restricted elevation. A soft compressible, nonpulsatile mass with well-defined margins was palpable in the superior orbit.
Computed tomography (CT) showed a well-defined, lobulated mass in the extraconal superior orbit above the superior rectus-levator palpebrae superioris complex, extending up to mid-orbit, showing early and homogenous enhancement with contrast with a quick washout [Figure 2]a. Magnetic resonance imaging (MRI) showed the lesion to be isointense on T1 and hyperintense on T2 weighted images with homogenous contrast enhancement and small flow-void signal areas [Figure 2]b.
|Figure 1: Clinical photograph of the patient showing right superior periorbital fullness with a downward displacement of the eyeball|
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|Figure 2: (a) CT scans coronal view showing a well-defined mass in the extraconal superior orbit with a homogenous contrast enhancement. (b) MRI sagittal view, T2 weighted image showing a well circumscribed and lobulated mass in the superior orbit with flow-void signal areas|
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The lesion was approached extraperiostealy through a subbrow or the Benedicts incision and excised completely along with its pseudo capsule. The postoperative period was uneventful. There was no proptosis or downward displacement of the eyeball and ocular movements were normal. There was no evidence of recurrence at 1 year postsurgery and she is on a regular follow-up.
Gross examination showed a multilobulated pinkish mass measuring 27 × 21 × 14 mm [Figure 3]a. Cut-section was pinkish-gray with multiple areas of hemorrhage. Microscopic examination showed a well-circumscribed, encapsulated tumor with cellular and cystic areas. The tumor shows vessels of varying caliber, dilated to compressed, lined by flattened endothelium. Sinusoidal vascular components with branching patterns or the stag horn channels were noted [Figure 3]b. There was minimal atypia with very few mitotic figures. The perivascular and extracellular spaces show the presence of eosinophilic hyalinized acellular collagenous material. Immunohistochemistry showed staining of endothelial cells of blood vessels with CD 31 [Figure 3]c, diffuse cytoplasmic and membranous staining of tumor cells with CD 34 [Figure 3]d. Focal SMA (smooth muscle actin) positivity [Figure 3]e with background S-100 staining was also noted. Vimentin was positive [Figure 3]f. The morphological features were consistent with a diagnosis of benign hemangiopericytoma.
|Figure 3: (a) Gross photograph of the tumor following excision. Note the pinkish color, lobulation and the thin overlying capsule, (b) Microphotograph of the tumor showing a uniformly cellular tumor with a sinusoidal vascular component often forming branching or stag horn channels, (c) (H and E ×100) Immunohistochemistry microphotographs showing CD 31 positive (d), CD 34 positive (e), SMA positive (f), and Vimentin positive (all ×100)|
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| Discussion|| |
Orbital hemangiopericytomas most commonly present in adults with proptosis and mass effect, predominantly in the superior part of the orbit, unassociated with features of pain, infiltration or entrapment. ,, Painless nonaxial proptosis with intermittent upper lid swelling like in the present case has also been reported. , The tumor has been described in the literature as slow growing, nontender, nonpulsatile with symptomatic duration ranging from 1 month to several years, usually unassociated with visual symptoms. ,,,, Rarely intracranial extension and invasion into sinus cavities produce associated symptoms. The major differential diagnosis include capillary hemangioma, cavernous hemangioma, and schwannoma. ,,
Hemodynamically hemangiopericytomas have been shown to have a rapid circulation with a significant amount of blood shunting. This explains the angiographic features of early tumor blush and rapid venous outflow. , CT and MRI show these tumors as well-defined masses with homogenous contrast enhancement. The flow-void signal area on MRI reflects the feeding artery. ,
Complete surgical removal is mandatory with wide margins due to high rates of recurrence and malignant transformation. ,,,, Differential patterns of tumor extension and radiological findings influence the choice of the most appropriate surgical approach. Complete surgical removal along with the capsule is difficult not only owing to the highly vascular nature of the tumor but also because of possible local infiltration.  A tumor that is not completely removed has a tendency to late recurrences and more aggressive behaviors. Certain series have documented recurrences up to one third of all cases. 
The basic histopathological feature consists of a uniformly cellular tumor with a sinusoidal vascular component often forming branching or stag horn channels. The tumor can be divided as benign, borderline or malignant based on cellular atypia, mitotic figures, pleomorphism, necrosis, compression of vascular spaces and infiltrative margins. Additional findings include myxoid, storiform, and cystic components.  Immunohistochemical analysis using CD 34, CD31, SMA, S-100, factor VIII are used to aid the diagnosis. ,, A very recent study that looked into the reclassification of hemangioperictyoma suggest that orbital hemangiopericytoma and some cases previously designated as fibrous histiocytoma, giant cell angiofibroma of orbit, and solitary fibrous tumor have overlapping morphologic and immunohistochemical features and should be designated as a solitary fibrous tumor. 
The spectrum of aggressiveness of a tumor is unpredictable as even the more benign lesions may be clinically invasive or may later show malignant transformation on recurrence. ,, About 30% of orbital hemangiopericytomas have histopathological criteria consistent with malignancy but distant metastasis is uncommon.  Enzinger and Smith proposed that a tumor diameter more than 6.5 cm, mitotic figures >4/10 hpf, hemorrhage, necrosis, cellular anaplasia, and increased cellularity associated with thrombosis are the criteria of malignancy.  Adjunctive radiotherapy or chemotherapy may be of benefit in malignant cases or those that recur following primary excision. ,,, Takahashi et al. recommended external beam radiotherapy only when there is inoperable recurrence or metasatasis.  Overall owing to the rarity of this tumor there is no conclusive evidence supporting any such benefit. ,,, Since recurrences and the risk of metastasis are present even after many years following surgical removal, a life-long follow-up is ideal in these patients.
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[Figure 1], [Figure 2], [Figure 3]