S. Dekeyzer S. Nicolay E. De Smet pilocytic astrocytoma – pilomyxoid astrocytoma J.W. Van Goethem pleomorphic xanthoastrocytoma P. M. Pa rize l L. van den Hauwe B. Goraj K. Kamphuis-van Ulzen Antwerp University Hospital - University of Antwerp, Antwerp/BE AZ KLINA, Brasschaat/BE S. Gaudino: Rome/IT (University Medical Center St Radboud, Nijmegen/NL) overview • introduction • pilocytic astrocytoma • pilomyxoid astrocytoma • pleomorphic xanthoastrocytoma • morphological imaging features • non-morphological imaging features • differential diagnosis • take home messages introduction 2016 WHO classification • diffuse astrocytic and oligodendroglial tumors • other astrocytic tumors: localized/circumscribed • ependymal tumors • other gliomas • choroid plexus tumors • neuronal and mixed neuronal-glial tumors other astrocytic tumors: localized/circumscribed Louis DN et al. Acta Neuropathol 2016 circumscribed astrocytic tumors circumscribed astrocytic tumors • pilocytic astrocytoma: PA • pilocytic astrocytoma: PA – WHO, grade I – WHO, grade I • pilomyxoid astrocytoma: PMA • pilomyxoid astrocytoma: PMA – WHO, grade II – WHO, grade II • subependymal giant cell tumor: SEGA • subependymal giant •celllack tumor: IDH gene SEGA family alterations • frequently have BRAF alterations – WHO, grade I – WHO, grade I • pleomorphic xanthoastrocytoma: PXA • pleomorphic xanthoastrocytoma: PXA – WHO, grade II – WHO, grade II Louis DN et al. Acta Neuropathol 2016 Louis DN et al. Acta Neuropathol 2016 pilocytic astrocytoma: PA • most common pediatric CNS tumor • most common pediatric cerebellar tumor pilocytic astrocytoma WHO, grade I • association with neurofibromatosis type 1 (NF1) – PA is found in 15-21% of NF1 patients – optic pathway (nerve, chiasm) glioma (OPG) • < 6 years of age • M:F = 1:2 • 1/3 of patients with OPG have NF1 pilocytic astrocytoma: PA pilocytic astrocytoma: PA • prototype of low-grade circumscribed glial tumor • may arise throughout the neuraxis • certain sites are preferred – cerebellum (60%) – optic nerve and chiasm • may also occur in – hypothalamus – pons – tectum – cerebral hemispheres – medulla/spinal cord Gaudino S et al. Childs Nerv Syst 2016 Gaudino S et al. Childs Nerv Syst 2016 pilocytic astrocytoma: PA cyst with mural nodule • easy diagnosis in typical locations • left temporal lobe lesion – cerebellum – optic pathway • risk of misdiagnosis in other locations • growth pattern and contrast enhancement can resemble more aggressive and infiltrative lesions Gaudino S et al. Childs Nerv Syst 2016 from: Gaudino S et al. Childs Nerv Syst 2016 PA – imaging features general rules • imaging features vary with location imaging findings • 2 main types: – expansile: cerebellum, cerebral hemispheres • well-circumscribed, round-oval mass, solid and cystic components morphological features • hypointense on T1-wi, hyperintense on T2-wi and FLAIR • intense enhancement CT, MRI • calcifications and hemorrhage are rare – infiltrative: optic/hypothalamic lesions, brainstem, medulla Gaudino S et al. Childs Nerv Syst 2016 a 10-year-old girl with NF1 T1-wi T2-wi FLAIR T1-wi + Gd DWI ADC T2-wi imaging features - MRI cyst content on FLAIR • CE is thought to be due to the peculiar vascular wall of PA – endothelial cells have open tight junctions and fenestrae that allow conspicuous contrast medium extravasation – in 50% of cases, the wall of the cysts does not enhance, and half the time they do; the fluid content is isointense to FLAIR slightly hyperintense compared to cerebrospinal fluid • usually little or no surrounding edema pilocytic astrocytoma: PA pilocytic astrocytoma: PA typical vs atypical presentation typical vs atypical presentation • cerebellum: expansile, cystic mass with a mural • location: nodule – pons and medulla – tectal plate – cerebral hemispheres • optic pathway: infiltrative lesion, elongating and • morphology hypothalamus widening the optic nerve/chiasm Gaudino S et al. Childs Nerv Syst 2016 Gaudino S et al. Childs Nerv Syst 2016 pilocytic astrocytoma: PA PA has numerous oddities that can numerous oddities: simulate a more aggressive appearance • appear well circumscribed, but often infiltrate surrounding brain tissue (64%) • enhances intensely, although it is not a high-grade neoplasm • metastatic spread (rare) can occur, without associated increased mortality • may spontaneously resolve in patients with NF1 imaging findings non-morphological (MRI) features DWI, DTI, PWI, MRS Case courtesy: A. Rossi, Genova/IT Case courtesy: S. Gaudino, Rome/IT a 15-year-old girl • long-standing headaches, medication-resistent • CT (not shown): TC in the left thalamus FLAIR T2-wi GRE-T2* Case courtesy: S. Gaudino, Rome/IT T2-wi T1-wi +Gd T1-wi + Gd characteristic first-pass curve FLAIR T2-wi DWI Case courtesy: S. Gaudino, Rome/IT Case courtesy: S. Gaudino, Rome/IT • rCBV <1.5 • first-pass curve crosses the baseline normal brain tissue lymphoma/JPA meningioma glioma/metastasis? 䇺mother in law䇻 cerebellar 60% Case courtesy: S. Gaudino, Rome/IT cerebellar PA 4 predominant imaging patterns after Gd-injection • cystlike mass with an enhancing cyst wall and intensely enhancing mural nodule: 46% T1-wi T2-wi FLAIR • cystlike mass with a nonenhancing cyst wall and intensely enhancing mural nodule: 21% • predominantly solid mass with minimal to no cystlike components: 17% • necrotic mass with a central nonenhancing zone: 16% Pencalat P et al. J Neurosurg 1999 T1-wi + Gd DWI ADC cerebellar PA T1-wi T2-wi FLAIR T1-wi + Gd DWI ADC T2-wi FLAIR T1-wi + Gd NCCT CECT T1-wi + Gd T2-wi T1-wi + Gd cerebellar PA - DD hemangioblastomas • hemangioblastoma – older age group – flow voids, arising from serpiginous supplying vesselsl – peritumoral edema T1-wi T2-wi FLAIR – elevated rCBV, von Hippel-Lindau syndrome • ependymoma – plastic tumor: 4th ventricle outlet foramina • medulloblastoma – DWI Case courtesy: G. Wilms, Leuven/B T1-wi + Gd JPAJPA PWI: perfusion-weighted imaging rCBV = 8 -10 rCBV = 1.1 T1-wi T2-wi FLAIR ependymoma T1-wi + Gd T1-wiT1-wi + Gd FLAIR T1-wiT2-wi FLAIR medulloblastoma T1-wi + Gd DWIUMCN ADC 0692879 T1-wi + Gd UMCN 9628767 flow artifacts T1-wiT2-wi FLAIR T1-wi + Gd DWI UMCNADC 9628767 optic nerve T1-wi T2-wi FLAIR T1-wi + Gd DWI UMCNADC 9628767 infiltrative PAs optic pathway PA • homogeneous solid lesions • involve the optic chiasm, optic nerves, and optic – isointense in T1-wi tracts – heterogeneously hyperintense in T2-wi – variable contrast enhancement – cystic components may be seen • optic nerve (one or both nerves) – enlargement • location – elongation – optic nerve – buckling of the optic nerve – chiasmatic/hypothalamic PA – optic canal may be enlarged – bulbar PA – midbrain PA a 3.5-year-old boy a 3.5-year-old boy chiasmatic/hypothalamic PA • infiltrative, well-circumscribed solid mass • optic chiasm/optic tract • microscopically infiltrative, involving the chiasmatic/hypothalamic hypothalamus and thalamus and the 3rd ventricle • a variable cystic component may be present, especially in large tumors and sporadic PA • T2-wi: hyperintense to gray matter • contrast enhancement is usually moderate to marked; may be absent • fleck-like tumor calcifications may be observed T1-wi a 14-year-old girl 2005 T1-wi + Gd a 5-year-old boy 2015 T1-wiT2-wi FLAIR T2-wi FLAIR T1-wi + Gd T1-wi + Gd DWI ADC T1-wi T1-wi T2-wi T1-wi +Gd T1-wi + Gd T2-wi T1-wi T1-wi +Gd chiasmatic/hypothalamic PA • when the tumor is mostly solid, PA should be differentiated from: – pilomyxoid astrocytoma cerebral hemispheres – pituitary macroadenoma – germinoma – meningioma – … T1-wi T2-wi FLAIR T1-wi + Gd a 15-year-old boy T1-wi T2-wi FLAIR ER UZA: seizures T1-wi + Gd DWI ADC T1-wi + Gd T1-wi T2-wiT2 wi FLAIR T1-wi + Gd GREDWIDWDW T2*I ADC cerebral hemispheres typical ‘cyst and mural nodule’ configuration • DD with ganglioglioma and pleomorphic xanthoastrocytoma • ganglioglioma – temporal lobe – cortical involvement brainstem - medulla – intratumoral calcifications – scalloping of the overlying calvarium • pleomorphic xanthoastrocytoma – temporal lobe – cortical involvement – intratumoral calcifications – scalloping of the overlying calvarium – meningeal involvement: dural tail sign solid PA – other low- grade and high-grade gliomas From: Gaudino S et al. Childs Nerv Syst 2016 brainstem PA diffusely infiltrative gliomas vs focal gliomas – considered focal when they occupy <50 % of the axial brainstem diameter – diffuse when they are >50 % of the brainstem diameter, and poorly demarcated T1-wi T2-wi FLAIR • focal gliomas: – exophytic that project dorsally into the fourth ventricle – are frequently PA • diffusely infiltrative brainstem/pontine gliomas – infiltrative fibrillary astrocytoma – expand the entire pons T1-wi + Gd DWI ADC pilomyxoid astrocytoma: PMA • a newly described neoplasm • originally considered just a "juvenile" variant of PA pilomyxoid astrocytoma • now recognized as a distinct entity • unique histological appearance • differs from PA in its presentation as well as its WHO, grade II clinical course Osborn AG. Osborn’s brain pilomyxoid astrocytoma: PMA pilomyxoid astrocytoma: PMA • may occur anywhere along the neuraxis imaging • strong geographic predilection for the suprasellar • imaging findings of PMA are similar to those of PA!!! region – tumors often display solid and cystic components • 60% center in the hypothalamus/optic chiasm, often – T2 signal intensity and ADC values are generally higher in PMA, reflecting the higher proportion of myxoid matrix in extending into both temporal lobes these tumors • 40% of PMAs occur in atypical locations,