|Year : 2019 | Volume
| Issue : 3 | Page : 719-721
Solitary fibrous tumor of the orbit: Computed tomography and histopathological findings
Asli Tanrivermis Sayit1, Muzaffer Elmali1, Adem Gul2, Yurdanur Sullu3
1 Department of Radiology, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey
2 Department of Ophthalmology, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey
3 Department of Pathology, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey
|Date of Web Publication||29-May-2019|
Dr. Asli Tanrivermis Sayit
Department of Radiology, Faculty of Medicine, Ondokuz Mayis University, Atakum, Samsun 55139
Source of Support: None, Conflict of Interest: None
A solitary fibrous tumor is a rare spindle cell neoplasm originating from the mesenchyme. This type of tumor of the orbit is very uncommon and can be misdiagnosed as a hemangiopericytoma, fibrous histiocytoma, meningioma, or neurofibroma. We report an orbital solitary fibrous tumor in an 18-year-old male, with slow-growing swelling in the right orbital region. An orbital contrast-enhanced computed tomography scan showed heterogeneously enhancing right extraconal inferomedial mass, with no evidence of calcification or bone destruction. The lesion was surgically excised without complications. Based on microscopic and immunohistochemical findings, the mass was finally diagnosed as a solitary fibrous tumor. These tumors should be preoperatively differentiated from other spindle cell tumors of the orbit, and radiological imaging methods are useful in the differential diagnosis but are nonspecific. Therefore, histopathological and immunohistochemical staining features are more useful for the diagnosis of solitary fibrous tumors, especially CD34 staining.
Keywords: CD34, computed tomography, fibrous tumor, orbit, spindle cell
|How to cite this article:|
Sayit AT, Elmali M, Gul A, Sullu Y. Solitary fibrous tumor of the orbit: Computed tomography and histopathological findings. J Can Res Ther 2019;15:719-21
| > Introduction|| |
Solitary fibrous tumors are uncommon spindle cell tumors of mesenchymal origin that most often arise from the pleura. However, this type of tumor can also occur in other areas of the body, such as the lung, mediastinum, pericardium, peritoneum, retroperitoneal space, pelvis, adrenal gland, kidney, liver, periosteum, salivary gland, thyroid gland, lacrimal gland, breast, and orbit. An orbital solitary fibrous tumor is rare, benign, and slowly progressive. It is usually seen in the fifth decade but can range from 9 to 77 years old, with a slight male predilection. First recognized and fully characterized in 1994 by Westra et al., about sixty cases of orbital solitary fibrous tumors have been reported in literature to date. However, these tumors might have been underdiagnosed in the past due to their rarity in the extrapleural organs and histological similarity to other spindle cell tumors. The number of reported cases has been increasing due to the development of new immunohistochemical methods. Here, we report the case of an orbital solitary fibrous tumor in an 18-year-old male, along with clinical, radiological, and histopathological findings.
| > Case Report|| |
An 18-year-old male presented to our clinic with complaints of swelling of the right eye over the previous few months. Ophthalmological examination showed mild swelling on the inferomedial side of the right eye; however, fundoscopic examination was normal. This patient had no history of trauma and his overall medical history was unremarkable. An orbital contrast-enhanced computed tomography scan showed a 2.5 cm × 2 cm × 1.5 cm heterogeneously enhancing right extraconal inferomedial mass, with no evidence of calcification or bone destruction [Figure 1] and [Figure 2]. The mass was compressing the eyeball, and the boundaries of the medial rectus muscles could not be distinguished. The other extraocular muscles and optic nerve were normal. The lesion was surgically excised without complications, and the microscopic examination of the tumor showed spindle-shaped cells [Figure 3] and [Figure 4]. The immunohistochemical examination showed positive staining for vimentin, CD99, and CD34 but was negative for smooth muscle actin, epithelial membrane antigen, and CD31. Based on these findings, the mass was finally diagnosed as a solitary fibrous tumor.
|Figure 1: Axial contrast-enhanced orbital computed tomography scan showing a well-demarcated extraconal inferomedial orbital mass with heterogeneous enhancement|
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|Figure 2: Coronal contrast-enhanced orbital computed tomography scan showing compression of the eyeball. The medial rectus muscle could not be distinguished from the lesion|
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|Figure 4: Oval- to spindle-shaped cells can be seen around the hemangiopericytoma-like vessels (H and E, ×200)|
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| > Discussion|| |
An orbital solitary fibrous tumor is usually benign, slow growing, and nonaggressive. These patients often present with slowly growing unilateral painless proptosis, inducing severe facial deformity, which may be associated with eyelid swelling, visual disturbances, a palpable mass, tearing, and ptosis. A solitary fibrous tumor may occur within any orbital space, including the intra- and extra-conal space, lacrimal gland fossa, lacrimal sac area, and eyelids., Yang et al. reported that most of these lesions (10/15 [66.7%]) are located in the extraconal space, with a predilection for the superolateral quadrant, adjacent to the lacrimal gland. In our case, the lesion was seen in the extraconal space, adjacent to the medial rectus muscle.
An orbital solitary fibrous tumor presents as a well-defined soft-tissue mass on computed tomography scans. It is low to isodense with the extraocular muscles, with significant enhancement after administering a contrast agent. Remodeling of the adjacent bones can be seen with long-standing orbital solitary fibrous tumors. However, these tumors do not lead to destruction of the adjacent bone, with the exception of fast-growing recurrent lesions. Unfortunately, imaging findings are nonspecific for soft-tissue tumors of the orbit, and they may not be clearly distinguishable from other lesions.
The differential diagnosis of a solitary fibrous tumor includes other tumors that cause proptosis, such as hemangiomas, fibrous histiocytomas, nerve sheath meningiomas, schwannomas, and hemangiopericytomas. The differential diagnosis between an orbital solitary fibrous tumor and hemangiopericytoma is particularly important, since the treatment approach for hemangiopericytoma is different due to its propensity for recurrence and metastasis. An orbital hemangiopericytoma is typically located in the extraconal space, adjacent to the paranasal sinuses. These lesions are usually lobulated and well circumscribed, and aggressive lesions can cause bony erosion; however, calcification is rare. Hemangiopericytomas show marked arterial enhancement and early venous phase enhancement, with rapid washout in multiphase computed tomography.
The pathogenesis of hemangiopericytomas remains controversial; however, they are thought to have the same cellular lineage as solitary fibrous tumors, and some pathologists believe that many of these lesions are best regarded as such. A hemangiopericytoma appears histologically as a dense hypercellular tumor with spindle-shaped cells  and shows weak and patchy immunohistochemical staining for CD34. A solitary fibrous tumor shows positive staining for CD34, which can be negative in malignant cases; therefore, the clinical, radiological, histopathological, and immunohistochemical staining features should be considered together in the differential diagnoses of hemangiopericytomas and solitary fibrous tumors.
In our case, the lesion was considered to be benign, and because the margins were well defined without bony destruction and remodeling, it was excised surgically without complications. It was finally diagnosed as a solitary fibrous tumor based on the histopathological and immunohistochemical staining features.
The standard treatment for solitary fibrous tumors is surgical excision, and recurrence is rare, but it usually follows an incomplete initial excision. In addition, chemotherapy and radiotherapy can be performed after surgical excision in locally invasive lesions. Although most orbital cases are benign, local invasion, recurrence, and distant metastasis have been reported in pleural solitary fibrous tumors. Although malignant transformation can be seen in these orbital tumors, distant metastasis is extremely rare, and there has been only one reported case of distant metastasis from a primary orbital solitary fibrous tumor., Nuclear atypia, increased cellularity, necrosis, and the presence of more than 4 mitoses per 10 high-power fields are considered to constitute malignancy.,
Orbital solitary fibrous tumors are rare and usually seen in the fifth decade, but the patients can range from 9 to 77 years old. These tumors should be preoperatively differentiated from other spindle cell tumors of the orbit, and radiological imaging methods are useful in the differential diagnosis but are nonspecific. Therefore, histopathological and immunohistochemical staining features are more useful for the diagnosis of solitary fibrous tumors, especially CD34 staining.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
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