A child presents with raised ICT, on CT scan a lesion is seen around foramen of Monroe and multiple periventricular calcific foci. What is the most probable diagnosis?
Ans. c. Subependymal giant cell astrocytoma (Ref: Osborn 3/e p 583-571, 562, 432: Wolfgang 7/e p 334)Most probable diagnosis in a child with raised ICT, lesion around foramen of Monroe and multiple periventricular calcific foci on CT scan is subependymal giant cell astrocytoma."Foramen of Monro (FM) is a Y-shaped structure that connects the two lateral ventricles with the third ventricle. FM masses are uncommon in young children. Subependymal giant cell astrocytoma (SGCA) occurs in older children and young adults with tuberous sclerosis. Pilocytic astrocytoma also occurs in this age group. Subependymoma and central neurocytoma occurs in adults. All FM masses can cause obstructive hydrocephalous and lead to raised intracranial tension."Well Delinated Intraventricular-Mass around Foramen of Monro with Calcification and Obstructive HydrocephalusSubependymal Giant Cell AstrocytomaCentral NeurocytomaEpendymomaSubependymoma* Occurs in older children and young adults (<20years)Q* Lateral wall of lateral ventricle overlying head of caudate nucleus near foramen of Monro.* Features of tuberous sclerosis like cortical tubers and sub ependymal hamartomatous nodules* Large, multinucleated giant cells with GFAP reactivity and/or neuron specific enolase and swollen astrocytes with abundant glossy eosinophilic cytoplasm* Heterogenous (cystic and heavilly calcified) vascular mass showing strong/intense but heterogenous contrast enhancementQ.* Occurs in young adults, rare in children and older adults.* Exclusively in lateral ventricle near septum pellucidum and FM.* Indistinguishable from oligodendroglioma on light microscopy but demonstrate neuronal origin on electron microscopy (synapse, process, granules and microtubules) and immunohistochemistry (enolase and synaptophysin).* Heterogenous (multiple small cyst and heavy calcification) mass with mild to moderate inhomogenous contrast enhancement.* More common (60%) infratentoral/ posterior fossa tumors (in 4th ventricle mostly) are plastic ependymomas which occur predominantly in 1-6 years children.* Less common infratentoral (40%) tumors arise near atrium of left ventricle or foramen Monro, which occur predominantly in 2nd through 4th decade.* Perivascular pseudorosette, peritumoral edema and CSF seeding (mainly in infratentorial).* Heterogenous (mixed density/ intensity; due to heavy calcification and cyst) mass with peritumoral edema (hypodense halo on CT) and mild to moderate but heterogenous contrast enhancement.* In middle and elderly adultsQ* 4th ventricle (lower medulla) > frontal horn of lateral ventricle near septum pellucidum and FM* Avascular, homogenous, grade I tumor; although large tumors may contain calcification and microcystic changes (less common).* Homogenous, avascular/ hypovascular mass with variable no or minimal contrast enhancementQ.Subependymal Giant Cell Astrocytoma (SGCA)SGCA is a low grade (WHO grade I) tumor that occurs almost exclusively in patients with tuberous sclerosisQ; 10- 15% patients of TS develop SGCA.Arise from subependymal nodules located on the lateral walls of lateral ventricles overlying the head of caudate nucleus.The tumor does not invade the underlying caudate head but rather grows exophytically into the ventricular lumen near the foramen of MonroQSGCA is sharply delineated lobulated heterogenous tumor.Intratumor heavy calcification is commonQ and tumors are often vascular.SGCA almost always occur at foramen of MonroQ, and most patients become symptomatic before age 20 due to obstruction of foramen of MonroQ leading to raised ICT or obstructive hydrocephalus.Diagnosis:Imaging features of SGCA include: heterogenous (partially cystic, partially heavily calcified) mass at foramen of Monro which shows strong but heterogenous contrast enhancement.
Central neurocytoma
Ependymoma
Subependymal giant cell astrocytoma
Ganglioglioma
Central Nervous System Tumors