Presentations

Abstract

Introduction: Primary intraventricular lesions are rare among all intracranial tumors, accounting for less than 2% of such lesions. These lesions originate within the ventricular system of the brain, from structures such as the septum pellucidum, choroid plexus, and walls of the lateral, third, and fourth ventricles. The differential for such lesions encompasses a wide range of pathologies, for which demographic, clinical, and imaging findings can help in the identification of appropriate diagnoses. Neuroimaging with computed tomography (CT) and particularly magnetic resonance (MR), holds a key role in the diagnosis of intraventricular masses. We report a case of an adult patient with a non-enhancing intraventricular mass suspicious for a central neurocytoma followed by a brief literature review of the imaging features of intraventricular lesions.

Case Information: A 39-year-old female presented to the emergency department with an acutely worsening headache and vomiting. The patient had a Glasgow Coma Scale rating of 14 and was able to follow simple commands on the initial exam, however, further evaluation was complicated by acute obtundation and confusion of the patient. Prompt non-contrast CT imaging of the head revealed a heterogenous mass with areas of hyper-attenuation, centered right of midline around the right thalamus and third ventricle with possible hemorrhagic component. There was apparent extension into the ventricles with obstructive hydrocephalus with dilation of the posterior horn of the third ventricle, and an associated midline shift. Repeat CT imaging demonstrated drooping of the cerebellar tonsils and herniation into the foramen magnum. The patient was transferred to the ICU with prompt placement of an external ventricular drain for decompression. MR Imaging of the brain revealed that the mass was intraventricular and arose from the atrium of the right lateral ventricle, crossing midline with mass effect on the septum pellucidum, measuring 5 cm. The mass demonstrated heterogenous signal on T2-weighted FSE (fast spin echo) imaging with largely hypointense signal on SWI (susceptibility weighted imaging) suggesting hemorrhage. On T1-weighted imaging, the mass was hypointense with scattered hyperintense pre-contrast signal. The central portion of the mass was predominately non-enhancing, with some marginal peripheral enhancement related to displaced choroid plexus. Primary differential diagnosis for minimal to non-enhancing intraventricular masses includes central neurocytoma with hemorrhage, as well as possibly a subependymoma with hemorrhage. Given the clinical status of the patient, however, the patient was transitioned to comfort measures and expired prior to histopathologic confirmation.

Discussion/Clinical Findings: Central Neurocytomas comprise <0.5% of all primary brain lesions and are much more commonly intraventricular than extra-ventricular. Such lesions are typically found in the anterior lateral ventricles attached to the septum pellucidum or arise from the ventricular wall. Most commonly, the lesions are noted near the foramen of Monro, but have been noted in lateral and third ventricles. These lesions are associated with obstructive hydrocephalus. Prognosis is typically good; however, rarer cases are associated with death and hemorrhage. Additionally, these lesions normally present around the third decade of life, with no gender predominance. On CT imaging, these lesions typically are hyperdense to the surrounding parenchyma, with calcifications and/or intratumor cystic structures. MR imaging typically demonstrates heterogenous lesions on T1-weighted imaging that are isointense with gray matter and demonstrate mild enhancement, while T2-weighted imaging demonstrates hyperintense lesions with multiple cystic structures resembling a "bubbly" or "Swiss-cheese" appearance with attenuation on FLAIR (fluid attenuated inversion recovery). On SWI, hemorrhage occurs on large tumors, and the lesions typically demonstrate diffusion restriction on DWI (diffusion weighted imaging). The characterization of intraventricular lesions using MR and CT features is critical for diagnostics, prognostics, and management. Thus, a summary of key imaging features of common intraventricular masses is highlighted in this study, including focal solid lesions (such as ependymoma, subependymoma, subependymal giant cell astrocytoma, choroid plexus papilloma), focal cystic lesions (colloid cyst, epidermoid cyst, ependymal cyst), infectious or inflammatory lesions, and metastases.

Conclusion: This report highlights an uncommon poor outcome of a central neurocytoma with hemorrhage, which otherwise has a relatively positive prognosis. As a result, the case emphasizes the importance of accurate and early identification of lesions using imaging in conjunction with clinical findings. The review portion of this study provides a comprehensive overview of key imaging features for the broad differential of intraventricular lesions which can guide diagnosis. Further research and reporting of rare cases should be undertaken to solidify the characterization of intraventricular lesions on imaging.