giovedì 9 novembre 2006
Figure 1 and Figure 5: T1 axial and coronal images demonstrate the soft tissue mass iso-intense to the adjacent muscles located predominantly in the extraconal plane with minimal intraconal extension.
Figure 2: T1 coronal post contrast with fat saturation demonstrates enhancement of the cavernous hemangioma.
Figure 4: T1 axial postcontrast image demonstrates peripheral hypointense margin from pseudocapsule (arrow at the site of pseudocapsule).
Figure 3: T2 coronal images demonstrating thin septa within the cavernous hemangioma.
Figure 6: Catheter angiogram in arterial phase does not show any feeding arteries.
Figure 7: Catheter angiogram delayed phase shows pooling of the contrast within the cavernous hemangioma.
Diagnosis: Cavernous Hemangioma
Cavernous hemangioma is the most common congenital vascular malformation of the orbit. Female predominance is appreciated with female to male ratio as high as 7:3. Hormonal factors have been implicated as there is more rapid growth during pregnancy. They grow slowly and are composed of multiple endothelial and smooth muscle lined vascular channels. Cavernous hemangiomas are well circumscribed round or oval lesions with well defined margins. They have a pseudo capsule from the surrounding compressed tissue.
The common clinical presentation is painless proptosis. Diplopia, visual impairment, increased intraocular pressure are seen with larger lesions.
Cavernous hemangiomas are more often intraconal. Larger lesions have extraconal extension. Primary extraconal lesions are also reported. Intraosseous hemangiomas are rare.
CT demonstrates the location of the lesion and micro calcifications. Phleboliths and macroscopic calcifications are rare. Remodeling of the bone is seen in long-standing cases. On MRI homogeneous soft tissue mass, which is isointense to the muscle on T1WI and hyperintense on T2WI with well-defined septations, can be seen especially in large lesions. Hypointense pseudo capsule is very visible along the periphery of the lesion.
Heterogeneous patchy enhancement is seen with contrast with more homogeneous enhancement on delayed imaging. Angiography demonstrates no obvious distinct tumor blush during the arterial phase. Contrast puddling is seen, which extends to the late venous phase, essentially isolated from systemic circulation.
Treatment options include observation only for stable lesions and lesions without significant symptoms. Intralesional laser, cryosurgical and radio surgical techniques are other alternatives in addition to surgery. Surgical resection is indicated for visual disturbance, cosmetic reason, and any symptoms related to mass effect. Recurrence rate is very low after surgery.