Meningioma originating and developing in the tela choroidea of the third ventricle. Its CT and angiographic findings (author's transl)

Abstract

Meningioma in the tela choroidea of the third ventricle is rare. The purpose of this paper is to report CT and angiographic findings of this rare condition in a 40-year-old female. Precontrast horizontal section CT disclosed an isodense mass in the pineal region, compressing the posterior portion of the third ventricle. The lateral ventricles and anterior portion of the third ventricle were dilated. This isodense mass was markedly enhanced by contrast infusion. Postcontrast coronal section CT at the level of the pineal region showed a lobulated, homogeneously enhanced, high density mass between the bodies of the lateral ventricles. The mass extended to the right of the third ventricle, and compressed and shifted its upper portion to the left. Postcontrast midsagittal section CT disclosed a lobulated, homogeneously enhanced, high density mass in the posterior portion of the third ventricle just anterior to the great vein of Galen. Right carotid angiography showed that the junction of the internal cerebral and thalamostriate veins was located in the midline, but the midportion of the internal cerebral vein was displaced laterally and markedly elevated. The posterior portion of the internal cerebral vein was markedly displaced laterally. Left carotid angiography showed that the septal vein and anterior portion of the internal cerebral vein were located in the midline, but the posterior portion of this vein was markedly displaced laterally. Vertebral angiography was remarkable. The pretectal segment of the right medial posterior choroidal artery was displaced laterally and markedly antero-inferiorly, giving off a branch to the tumor. The plexal segment of this artery was displaced slightly laterally and markedly antero-inferiorly, and ran in an arcuate fashion with antero-inferior convexity in the lateral projection, indicating that this vessel runs along the antero-inferior margin of the tumor, which appeared as a homogeneous tumor stain in the late venous phase. The pretectal and plexal segments of the left medial nosterior choroidal artery were laterally and inferiorly displaced. The posterior pericallosal artery running along the outer surface of the splenium of the corpus callosum showed an almost normal configuration but a branch running along the inferior surface of the splenium of the corpus callosum was hypertrophic and slightly displaced posteriorly. Fine twigs of this artery supplied the tumor. All these findings indicated a tumor originating and developing in the tela choroidea of the third ventricle. This diagnosis was confirmed by surgery. Anatomical considerations of the tela choroidea of the third ventricle are included. CT facilitated detection of the rough location and histological features of the tumor. Carotid and vertebral angiographies were utilized in detailing the three-dimensional gross anatomical relationship between the tumor and the surrounding brain structures. Vertebral angiography also contributed to predictions of the histology of the tumor.