Dural Infantile Hemangioma Masquerading as a Skull Vault Lesion

SUMMARY: We describe a case of intracranial dural IH initially diagnosed as a primary skull vault lesion hemangioma due to associated focal hyperostosis. Histopathologic examination of the dural component confirmed IH. The case is discussed in the context of IH within the neural axis.


Discussion
IHs (previously termed "capillary hemangiomas") are the most common vascular tumors of infancy. They are benign neoplasms of endothelial cells that rapidly proliferate initially, usually in the first 5 months of life, followed by a plateau phase and slow involution. 1 On histologic examination, these lesions comprise lobules of tightly packed endothelial cells forming capillary-like structures, separated by septa of fibrous connective tissue. 1,2 Identification of the Glut-1 protein on immunohistochemical staining is used to distinguish these lesions from other vascular lesions. 1 More commonly, they involve the skin and soft tissues. Involvement of the neural axis is rare.
Our initial interpretation of the imaging findings was that this was primarily a bony lesion, an intradiploic IH, with hyperostosis and secondary dural reaction. However, the features were atypical and of concern. There was hyperostosis but no abnormal diploic space enhancement or large abnormal diploic space vessels. The dural reaction was too extensive and florid to be a secondary dural reaction to an intradiploic IH or an essentially benign-appearing bone lesion. Meningioma was considered a possibility, given the florid hyperostosis and dural thickening; however, the appearance was also atypical for this condition. The extensive dural thickening on imaging, therefore, raised concern of a primary dural lesion of sinister etiology.
Hydrocephalus was been described in 10% of intracranial IHs. It is uncertain whether this represents an association with or a consequence of the hemangioma. It could be postulated that thrombosis of small venous structures associated with the hemangioma or the direct mass effect of the lesion alters local CSF flow dynamics, resulting in hydrocephalus. The mild ventricular dilation in our case may reflect such a prior CSF flow alteration because we postulated that this lesion was already involuting at diagnosis.
Given that IHs are self-limited, management is dependent on size, location, and any associated complications, which include visual and neurologic deficits for the intracranial lesions. Contemporary management of IH is with propranolol; however, systemic steroid and interferon therapy has been described. 12,13 In the absence of complicating features, observation in expectation of involution is favored.

Conclusions
We report a new entity of intracranial dural hemangioma, histologically confirmed by Glut-1 staining. The description of the imaging findings and pitfalls in diagnosing this lesion should be considered in assessing durally based lesions in childhood and should help to guide the management of this benign self-limiting lesion.