Unusual case of orbital encephalocele.

A 1-year-old boy had ophthalmologic findings of a retinoblastoma in the right eye. Noncontrast and contrast computed tomography (CT) demonstrated a characteristic calcified lesion of retinoblastoma in the right globe and a nonenhancing, well circumscribed, extraconal mass in the superolateral aspect of the left orbit (fig. 1 A). This mass, measuring 18 H, displaced the optic nerve medially. An area of hyperostosis was demonstrated in the lateral bony wall of the left orbit adjacent to the lesion, and there was widening of the superior orbital fissure (fig . 18). Plain radiographs, including Caldwell views, were normal. Ten days after the initial scan, 4.5 ml of metrizamide (concentration , 170 mg I/ml) was introduced into the basilar cisterns via a lumbar puncture, and routine axial and coronal CT scans were obtained. The study demonstrated a rim of metrizamide surrounding the soft-tissue mass, the density of which was unchanged from the earlier scan (figs . 1 C and 1 D). CT scans 4 hr later showed disappearance of the contrast material from the rim of the mass, with no increase in the overall density of the lesion . On the basis of this study, a diagnosis of encephalocele was made. Follow-up scans 19 months later demonstrated no change in the appearance or size of the left orbital lesion.