intraventricularneoplasms 161007063447

INTRADãnVENTRICULAR não thất III não thất bên hai NEOPLASMS bên, phù mô kẽ quanh não thất bên hai bên PRESENTED BY Dr Fahad Shaf • A variety of neoplasms may arise in the ventricular system • According to the lesion size and location, patients may be asymptomatic with the mass found as an incidental fnding at cross-sectional imaging or • may present with headaches, signs and symptoms of increased intracranial pressure, or a focal neurologic defcit Ventricular Anatomy • differential diagnosis of intraventricular neoplasms is broad To understand the different entities that can occur in an intraventricular location, it is important to understand the embryology, anatomy, and histologic structure of the ventricular system ependymal-lined outpouchings from the cranial end of the neural tube, which are called the telencephalic vesicles choroid plexus develops from an invagination of primitive pia-arachnoid and vessels into these vesicles, thus creating the choroidal fssures • The septum pellucidum is also lined by glial cells and residual neuronal precursor cells, from which the central neurocytoma may arise • The very vascular choroid plexus produces cerebrospinal fluid (CSF) and may give rise to primary neoplasms of the choroid plexus (choroid plexus papilloma, atypical choroid plexus papilloma, choroid plexus carcinoma); owing to its vascular supply, it may contribute to deposition of metastases in this location • Arachnoidal cap cells, which make up the arachnoid granulations, may become trapped within the choroid plexus during embryologic development; these cells can give rise to meningiomas IMAGING MODALITIES • Plain skull radiographs–May demonstrate calcification and evidence of raised intracranial tension • Plain and contrast enhanced CT–May help in characterization of the lesion confrming the presence of calcifcation MDCT may help in better localization through its multiplanar capability with the help volumetric data acquisition • Conventional ventriculography/CT ventriculography – It has become obsolete with the advent of MRI • MRI – It has transformed the way we look at intracranial lesions with its exquisite resolution and multiplanar capability • Angiography – Indicated in vascular malformations and for angioembolization MEDULLOBLASTOMA • MC malignant brain tumours in children • Commonly present as midline masses in the roof of 4th ventricle • Account for 12-25% of pediatric cns neoplasms ans 30-40% of posterior fossa tumours.In adults account for 0.4-1% of cns neoplasms • M:F =2:1 • Mean age of diagnosis is yrs • Growth is rapid hence present with over few weeks • 40% cases show CSF dissemination at the time of diagnosis  medulloblastoma in a typical location within the midline of the posterior fossa On imaging studies, medulloblastoma commonly appears heterogeneous, due to areas of hemorrhage, cyst formation, and occasional areas of calcifcation, as depicted here Leptomeningeal seeding, which is also illustrated here, is often seen in imaging studies • • • • NECT Solid mass in the 4th ventricle Ca2+ in upto 20% Small tumor cysts and hemorrhage in 40 to 50% • >90% enhance homogenously, occasionally may be patchy Chordoid Glioma •  WHO grade II, slow-growing glial neoplasm described in 1998 by Brat et al that involves the region of the anterior third ventricle and the hypothalamus These are rare lesions • patients typically present with hypothalamic dysfunction, homonymous hemianopsia, or increased intracranial pressure • The cell of origin is unknown, although there is speculation that chordoid gliomas may arise from the tanycytes, which are special ependymal cells located in the floor of the third ventricle • Chordoid glioma is a well-circumscribed ovoid lesion in the region of the anterior third ventricle and hypothalamus These neoplasms are hyperattenuating at Ct At MR imaging, chordoid gliomas are isointense to gray matter on T1-weighted images and hyperintense on T2-weighted images and enhance avidly after contrast material administration  Rosette-forming Glioneuronal Tumor • RGNT is a recently described WHO grade I, rare primary brain tumor It was included as a distinct glioneuronal neoplasm in the 2007 WHO classifcation of tumors of the central nervous system • These neoplasms demonstrate glial and neuronal differentiation, and it has been suggested that they arise from progenitor pluripotential cells of the subependymal plate • Imaging reveals a fairly well-circumscribed, heterogeneous solid and cystic mass classically centered on the fourth ventricle • Heterogeneous enhancement is seen on contrastenhanced images Intratumoral hemorrhage and calcifcation may occur • Although this is an uncommon neoplasm, the diagnosis of RGNT should be considered when a cystic neoplasm of the fourth ventricle is encountered in an adult  Axial T2-weighted image shows a predominantly cystic mass involving the fourth ventricle Layered blood is noted in the dependent portion. (c) Sagittal contrastenhanced T1-weighted image shows minimal enhancement involving the periphery of the lesion Hydrocephalus is presen Metastases • Intraventricular metastases account for 0.9%–4.6% of cerebral metastases • In adults, renal, colon, and lung carcinoma are the most common causes; in children, neuroblastoma, Wilms tumor, and retinoblastoma are most common • Renal cell carcinoma is remarkable in its ability to produce solitary metastases up to 50 years after identifcation of the primary lesion  • Intraventricular metastases are most common in the lateral ventricles but may also occur in the third ventricle and very rarely in the fourth ventricle •  Avid enhancement is usually seen on contrast-enhanced images, and vasogenic edema may be seen in the adjacent brain parenchyma Metastasis: CECT shows diffuse ependymal enhancement and hyperdense nodule in the left paraventricular region with edema in patient of carcinoma thyroid Colloid cyst of the third ventricle •  benign epithelial lined cyst with characteristic imaging features Although usually asymptomatic, they can rarely present with acute and profound hydrocephalus • Colloid cysts account for ~2% (range 0.5-3%) of primary brain tumours and 1520% of intraventricular masses 1-3  They are located at the foramen of Monro in 99% of cases 1 • The majority of cases are identifed in early middle age (30-40 years of age) although 8% of cases may be diagnosed in paediatric age 3 PATHOLOGY • Colloid cysts originate from abnormal folding of the primitive neuro-epithelium (the paraphysis elements) . They contain mucin, old blood (haemosiderin), cholesterol, and various ions, accounting for the wide range of imaging appearance • These cysts are lined by a single layer of columnar epithelium which produces mucin, which appears as a thick yellow green fluid when the cyst is open IMAGING FEATURES • On all modalities colloid cysts appear as a rounded, sharply demarcated lesion at theforamen of Monro, which range in size from a few millimetres to 3-4cm • ON CT typically seen as a well defned, rounded lesion at the roof of the 3rd ventricle: • unilocular • typically hyperdense • isodense and hypodense cysts are uncommon • calcifcation is uncommon  MRI • T1: variable ~50% high signal  the rest are hypointense or isointense to adjacent brain • T1 C+ (Gd): only rarely demonstrates thin rim enhancement, but usually this represents enhancement of the adjacent and stretched septal veins  • T2: variable most are of low T2 signal , related to thick "motor oil" consistency fluid  some have central low T2 and high peripheral T2 signal some are homogeneously high signal • FLAIR: cysts which are of low signal on T2 will appear similar to attenuated CSF on FLAIR, and are thus difficult to appreciate  CONCLUSION • Many of these lesions have similar patterns of signal intensity and contrast enhancement at imaging • However, the location of the lesion in the ventricular system—along with knowledge of the patient’s age, gender, and underlying conditions—will help narrow the differential diagnosis