Integrated Three-dimensional and Stereoscopic Imaging for Stereotactic Neurosurgery Planning

Figure 1-MRI, sagittal SE 600/20. Intrasellar hypointense mass extending into sphenoid sinus (arrow). Pituitary gland elevated, optic nerve not involved. A 48 year old woman had an MRI examination of the brain which confirmed the clinical diagnosis of multiple sclerosis. Incidentally, a cystic mass was noted in the sella turcica. A pharyngeal soft tissue mass containing cysts was also shown (Figs. 1, 2). A contrast enhanced CT scan additionally showed a diagonal conduit in the basisphenoid joining the pharyngeal mass to the cyst (Figs. 3, 4). Removal of this lesion was done via transphenoidal approach. Amber fluid was aspirated from a thin walled cyst. Its wall was partially excised. The histopathological diagnosis was Rathke pouch cyst. Rathke pouch is a diverticulum of the primitive oral ectoderm which anterior and posterior walls are precursors of the anterior lobe of the pituitary gland. A central portion or cleft may in some instances expand, giving origin to Rathke cysts. A spectrum of developmental disorders occurring in this area include craniopharyngiomas as the most complex ones, while Rathke cysts represent the simplest form. Figure 3-CT, coronal, bone window: Diagonal conduit extending from the floor of the sella to the undresurface of the basisphenoid. The CT and MR imaging findings consistently show a well defined, midline mass in the sella turcica with extension into the suprasellar cistern or into the sphenoid sinus. The density on CT and intensity on MRI are varied (1) depending on the protein concentration in the cyst. In our case, the cyst had a CSF-like signal, related to low protein concentration. The diagonal conduit seen in the basisphenoid represents persistence of Figure 2-MRI axial SE 2100/80. Homogeneous hyperintense sellar mass. Figure 4-CT, coronal, soft tissue window. Nasopharyngeal mass cysts. Expanded sella turcica with hypodense mass. the craniopharyngeal canal. This bony defect associated with a nasopharyngeal mass has been described with ectopia of the pituitary and other anomalies of the nose and palate (2), gigantism (3) and mostly with meningoencephaloceles (4). Usually asymptomatic and, as in the present case, a serendipitous finding, Rathke cysts may attain large size and compress the chiasma, hypothalamus and pituitary gland. The usual differential diagnosis is with craniopharyngioma, arachnoid cyst and cystic pituitary adenoma (1). Bibliography (1)Kucharczyk W et a). Rathke cleft cysts: CT, MR imaging and pathologic features. (4) Pollock JA et al. Transphenoidal and transethmoidal encephaloceles: a review of clinical and roentgen features in 8 …