Unusual lesion of the clivus: diagnosis and discussion

Abstract

DiagnosisBased on the imaging findings, the diagnosis of a primaryintraosseous cavernous hemangioma of the clivus was made,whichwasconfirmedafterbiopsyandsurgicalremovalofthelesion.DiscussionPrimary intraosseous cavernous hemangiomas (PICHs) ofthe skull are rare benign tumors that account for about 0.2–1% of all benign neoplasms of [1, 2]. They are typicallylocated in the parietal and frontal bones of the calvarium,whereas location in the craniofacial bones is less common(zygoma, maxilla, mandible, and vomer) [1, 2]. PICHs ofthe skull base and the clivus are extremely rare [1, 2].PICHs are usually solitary and most commonly occur inwomen in the second through fifth decades [1, 2].Histologically, hemangiomas are classified as cavernousand capillary hemangiomas [2]. Cavernous hemangiomasare composed of large dilated blood vessels separated byfibrous tissue, whereas capillary hemangiomas lack fibroussepta and have smaller vascular lumens. Calvarial heman-giomas are usually of the cavernous type, whereas vertebralhemangiomas are most frequently of the capillary type [3].The lesion is often discovered as an incidental finding onCT or MRI scan of the brain done for other reasons. Othersymptomsincludepainandvisibleorpalpablebonyhardmassof the calvarium or neurologic deficits in case of intracranialexpansion.Somepatientspresentwithperiodicdullheadachesthat may increase as the hemangioma expands [1].CT scan shows an intraosseous mass with a honeycombor sunburst pattern, very similar to a vertebral hemangioma.Expansion of the cortical bone may occur, but theperiosteum remains intact [1, 2]. Fatty tissue may be seenbetween the thickened trabeculae.The signal intensity on MRI is variable, depending on thequantity ofslow-moving venousblood and onthe ratio of redmarrow to converted marrow present within the lesion [1, 2].Lesions with a high fatty content are of high signal intensityon T1-weighted images (WI), such as in our case. Largerlesions tend to have a low signal intensity on T1-WI [1]. OnT2-WI, a high signal intensity may be caused by pooling ofblood or slow-flowing blood. Correlation between MRappearance on T1- and T2-weighted images and histologicalfindings from autopsy specimens has only been performed instudies with a limited number of patients [4]. Cavernoushemangiomas typically enhance after administration ofgadolinium contrast [1, 2].CT scan is more helpful than MRI in planning surgerybecause the extent of the lesion is better evaluated on bonewindows [5]. PICHs of the clivus may mimic other morecommon tumors of the skull base, particularly when theclassic imaging features are absent [2].