Contributed by A. Martina Messing-Jünger, MD1, Markus J. Riemenschneider, MD2, Guido Reifenberger, MD, PhD2
1Neurosurgical Clinic, and 2Department of Neuropathology, Heinrich-Heine-University, Düsseldorf, Germany
Published on line in June 2005
A previously healthy 21-year-old female presented with permanent tinnitus, vertigo and nausea lasting for two months. Physical examination did not reveal any neurological deficits. Her family history was negative. All blood tests, including serum levels of the germ cell tumor markers alpha-fetoprotein (1.1 µg/l) and beta-human chorion gonadotropin (< 2 mIU/ml), were normal. Magnetic resonance imaging (MRI) of the brain demonstrated a small, partially cystic, contrast-enhancing mass in the posterior part of the third ventricle. Fig. 1a shows the tumor (arrow) on a contrast-enhanced T1-weighted sagittal MRI scan. Fig. 1b demonstrates a coronal section through the tumor. The tumor did not result in an obstruction of the cerebrospinal fluid flow. No further intracranial lesions were present. We additionally performed a digital subtraction angiography, which revealed a variant of the vein of Galen but no pathological vascularization of the intraventricular mass. The tumor was resected via an infratentorial supracerebellar approach. The postoperative course was uneventful.
Histological investigation showed a moderately cellular tumor that consisted of spindle-shaped tumor cells with elongated-ovoid nuclei and long, wavy processes (Fig. 2a). Mitoses and necroses were absent. The tumor matrix was densely reticulin rich (Fig. 2b). Myelinated nerve fibers were not detected. Focally, the tumor tissue involved the plexus choroideus and contained conchoidal calcifications of the type seen in plexus. Immunohistochemistry revealed a strong and diffuse expression of protein S-100 (Fig. 2c). Immunostains for glial fibrillary acidic protein and epithelial membrane antigen were negative. The Ki-67 (MIB-1) labeling index was low (<1%) (Fig. 2d).