Other Rare Vascular Tumors of the Orbit

Abstract

Hemangiopericytoma

• Hemangiopericytoma, now referred to as Solitary fibrous tumor, is an uncommon tumor arising from spindle cells of mesenchymal origin. Though the most common site of origin of such a tumor is pleura, these tumors can also be observed in the extra pleural locations of the body such as, the lung, mediastinum, peritoneum, pericardium, retro peritoneum, pelvis, adrenals, kidney, periosteum, salivary gland, thyroid, breast, and orbit. On histopathological studies, it shows a patternless growth pattern characterized by bland spindle-cell proliferation with alternating hyper- and hypo-cellular areas and a focal hemangiopericytoma-like vascular pattern.

• On computed tomography, it appears as a well-defined soft tissue mass which is low or isodense compared to the extra ocular muscles but shows bright contrast enhancement.

• Magnetic resonance imaging depicts iso intensity on T1 weighted and iso to hypo intensity on T2 weighted images, but some lesions may show heterogeneous hyper intensity or cystic appearance also. As mentioned above, it shows intense enhancement.

• Immunohistochemistry can confirm the diagnosis, following which, complete tumor resection is the treatment of choice.

Angiosarcoma

• Angiosarcoma is a rare, frequently misdiagnosed vascular tumor which is a deadly masquerader and bears high propensity for local recurrence and metastasis.

• It is a moderately differentiated tumor with nuclear atypia, distinct vascular channels of irregular size and shape, communicating focally to form a reticular network of sinusoids which dissect through the collagen of dermis.

• Computed tomography of angiosarcoma can mimic other vascular tumors and thus is useful only to determine the extent of the lesion and does not aid in diagnosis.

• Treatment aims at complete surgical resection to prevent recurrence and metastases, but due to its multifocal and aggressive nature, this goal might not be achieved. It is relatively resistant to other adjuvant modalities like chemotherapy and radiotherapy.

Hemangioblastoma

• Hemangioblastoma is a benign vascular tumor, chiefly of capillary size vessels which account for 1–2% of primary tumors in the central nervous system in the posterior fossa or the spinal cord. It is frequently associated with von Hippel-Lindau syndrome.

• It usually involves the retina and the optic nerve with rare orbital manifestations. It is a soft solid lesion arising from the substance of the nerve and not the overlying neural sheaths.

• Computed tomography shows a homogenous mass hyperdense to the vitreous and hypodense to the extra ocular muscles.

• Magnetic resonance imaging shows the mass to be isointense on T1 weighted scan and hyper intense on both T2 weighted scans and in fluid-attenuated inversion recovery imaging. The lesion also takes up contrast in a moderately homogenous to heterogenous fashion.

• For lesions associated with the optic nerve, the mainstay of treatment remains surgical resection following which the patient must be evaluated for other associated tumors in the von Hippel-Lindau umbrella such as cerebellar hemangioblastoma and renal cell carcinoma.