Chordoid glioma of the third ventricle attached to the optic chiasm. Successful removal through a trans-lamina terminalis approach

Investigacion -Unidad de Neurocirugia RGS

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Rodrigo Carrasco, Jose M. Pascual, Teresa Reina, Santiago Nieto, Juan Linera, Rafael G. Sola

1.- Introduction
Chordoid glioma of the third ventricle is a rare and relatively recently described neoplasm that has been assigned by the World Health Organization (WHO) to the group of “Tumors of Uncertain Origin”, as a glial grade II tumor [1,2]. Topographically, this tumor typically occupies the third ventricle-hypothalamic region as a solid, homogeneously enhancing mass, constituted by epithelial cells arranged in clusters and cords, embedded within a mucinous matrix [3,4]. Immunohystochemically, the lesion is characterized by its strong diffuse GFAP reactivity [5]. Due to the short number of cases reported to date, the exact origin and best surgical man- agement for this lesion remain unclear [6–9]. Surprisingly, for a lesion considered as a low-grade glioma and operated under standard microsurgical techniques, the overall outcome is rather poor, with a postoperative mortality reaching the 25% of the cases, and permanent hypothalamic morbidity affecting one out of four survivors [8]. The recurrence rate is also high, involving nearly the 20% of patients. These figures are probably related more to the uncertainty about anatomical relationships and degree of adherence of this tumor than to its biological behaviour. We present neuroradi- ological and surgical evidences obtained from a successfully removed chordoid glioma showing a definite band of tight attachment to the optic chiasm-lamina terminalis junction. A translamina terminalis approach allowed a safe detachment of the tumoral mass under continuous direct view, minimizing the potential distortions of the hypothalamic walls caused by surgical manipulations.
2.- Case report
A 53-year-old woman was transferred from another hos- pital to our neurosurgical department, for surgical evaluation of a large tumoral lesion occupying the third ventricle area. The patient symptoms had started one year ago, when she complained of sudden visual disturbances, confusion and dizziness. A relative had noticed that she did not recognize her name during phone conversations. The ophthalmologic exploration revealed a superior bitemporal quadrantanopsia without fundoscopy signs of papilledema. Endocrinologi- cal tests evidenced reduced plasmatic estradiol levels and an increased prolactin value of 1.7ng/ml. An obstructive hydrocephalus, caused by a tumor occupying the third ven- tricle cavity, was then observed in the MRI study, and a ventriculoperitoneal shunt was implanted with resolution of symptoms related to high intracranial pressure. On admis- sion in our department, the patient was alert and oriented in time and place, and did not show focal neurological deficits. The ophtalmologic study showed no changes in her visual field deficit yet an increased latency in the visual evocated potentials of both eyes was observed. The endocrinological investigations for pituitary functions were normal.
Computed tomography performed on admission revealed a 3 cm × 2.5 cm isodense mass centered at the third ventricle area, which enhanced homogeneously after contrast administration. No signs of active hydrocephalus were observed. On the high resolution 3T MRI study a rounded and well delimited lesion filling the third ventricle cavity was evidenced (Fig. 1A–B). It consisted mainly of a solid isointense mass on both T1 and T2 weighted images, associating some peripheral cystic regions that were hypo and hyperintense on T1 and T2 sequences respectively. The solid component enhanced homogeneously after Gadolinium administration.

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