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1. ASTROCYTOMAS & OLIGODENDROGLIOMA MODERATOR: DR.MANASA PRESENTOR: N.LAKSHMI CHAITANYA

2. Grading WHO grade I :  have low proliferative potential  and generally long progression-free survival.          - pilocytic and subependymal giant cell            astrocytoma WHO grade II:  All diffusely infiltrating astrocytomas are  at least  WHO grade II neoplasms.  Tumors with cytologic atypia alone are                considered  WHO grade II

3. If anaplasia and mitotic activity are also present, they are considered  WHO grade III                     Eg :  anaplastic astrocytoma Tumors that additionally demonstrate microvascular proliferation and/or necrosis are  WHO grade IV  neoplasms                   Eg : glioblastoma

4. AGE AND ASTROCYTOMAS Newborn/Infant Rare; Supratentorial > > infratentorial Large, bulky hemispheric mass Most common = glioblastoma • Less common = pilomyxoid astrocytoma • Rare = pilocytic astrocytoma Children/Young Adults Common • Infratentorial > supratentorial Pilocytic > diffusely infiltrating astrocytoma >subependymal giant cell astrocytoma (SEGA)

5. Middle-Aged/Older Adults The older the patient, the more malignant the astrocytoma • Glioblastoma > anaplastic > > diffuse astrocytoma • Usually involve hemispheric white matter • Posterior fossa very rare

6. Localized Astrocytomas   Pilocytic Astrocytoma  Pilomyxoid Astrocytoma  Subependymal Giant Cell Astrocytoma  Pleomorphic Xanthoastrocytoma   Anaplastic Pleomorphic  Xanthoastrocytoma  

7. Diffuse Astrocytomas   Diffuse Astrocytoma, IDH-Mutant  Diffuse Astrocytoma, IDH-Wild Type  Anaplastic Astrocytoma, IDH Mutant  Anaplastic Astrocytoma, IDH Wild-Type  Glioblastoma, IDH-Wild-Type  Glioblastoma, IDH-Mutant  Gliosarcoma   Pediatric Diffuse Gliomas  Diffuse Midline Glioma, H3 K27M Mutant 

8. Pilocytic Astrocytoma also known as Cystic cerebellar astrocytoma    m/c primary  brain tumour in children .  BRAF gene fusion  WHO grade - I    Peak incidence- 5-15 years m=f  Sporadic or syndromic NF 1 associated – m/c- optic nerve/tract – optic path way gliomas   

9. Location: m/c cerebellum  2nd m/c optic nerve/ chiasm&hypothalamus /3rd ventricle   pons and medulla if occurs at tectum they may cause aqueductal stenosis.

10. IMAGING CT - mixed cystic/solid or solid mass      Hypodense cystic areas with isodense solid component calcifications 10-20% Hemorrhage is rare On contrast :  cyst – no enhancement Mural nodule – enhances strongly.   solid enhancing mass with central necrosis/solid homogenous enhancement. cyst wall may have some enhancement

11. MRI

12. MRS- elevated choline , low  NAA and increased  lactate   peak 

13. Pilomyxoid Astrocytoma Rare , variant of  pilocytic astrocytoma. PMAs are usually negative for  BRAF . Mc location: suprasellar region -  hypothalamus/optic chiasm, often extending into both temporal lobes. Because of its more aggressive behavior and more frequent CSF dissemination, many neuropathologists consider PMA a grade II neoplasm. Large, bulky, H-shaped tumor . May extend laterally toward/into temporal lobes.

14. More common in infants, children < 2 years Often more aggressive behavior Occasionally may demonstrate progressive maturation to PA Some may dedifferentiate to glioblastoma CSF dissemination more common

15. Imaging PMAs are more often solid and are primarily hypodense on NECT .   Intratumoral hemorrhage is seen in nearly half of all cases; calcification is rare. T1WI  iso- to hypointense  T2/FLAIR hyperintense, reflecting the high proportion of myxoid matrix in these tumors  T2*  intratumoral hemorrhage (which is very rare in PAs.)

16. Diffusion restriction is absent PMAs demonstrate strong, generally homogeneous enhancement after contrast administration

17. Subependymal Giant Cell Astrocytoma WHO grade I astrocytic tumor that mostly occurs in patients with tuberous sclerosis complex (TSC). Nearly all SEGAs are located in the lateral ventricles , adjacent to the foramen of Monro. Calcification is common. Hemorrhage and necrosis are uncommon. Occurs in first two decades of life. Mean age at diagnosis is 11 years

18. Imaging Check for ancillary imaging findings of TSC. CT Findings.  SEGAs are hypo- to isodense , variably calcified lesions near the foramen of Monro  SEGAs demonstrate strong but heterogeneous enhancement . An enhancing lesion at the foramen of Monro on CECT scan should be considered SEGA until proven otherwise.

19. MRI  T1 iso-/hypointense, T2/FLAIR hyperintense May have prominent vascular "flow voids"(larger lesions) Strong, heterogeneous enhancement

20.                        SEGA                  SEN(MC) near the foramen of Monro along the lateral ventricle margins, especially the caudothalamic grooves SEGAs gradually enlarge SENs remain stable larger than 5 mm is more likely to be a SEGA than an SEN. progressive enlargement is sufficient to differentiate a SEGA from an SEN . CALCIFICATIONS + CONTRAST ENHANCEMENT + CALCIFICATIONS + CONTRAST ENHANCEMENT +

21. Pleomorphic Xanthoastrocytoma Rare glioma and  sometimes associated with cortical dysplasia and typically express neuronal markers. BRAF  point mutations(+)similar to pilocytic astrocytoma and ganglioglioma. Supratentorial;  superficial cortically based , seizure associated neoplasms. The temporal lobe is the most common site (40-50%), and involvement of the adjacent leptomeninges is common.

22. PXAs are generally tumors of children and young adults; mean age at diagnosis is 22 years. Because of its characteristic superficial cortically based location, the most common presentation is longstanding epilepsy. Imaging well-delineated, peripheral, cortically based mass that contacts the leptomeninges. A "cyst + nodule" configuration  is present in 70% of cases, and a predominantly solid mass with intratumoral cysts is seen in 30%

23. Adjacent bone remodelling present, calcifications present ; intratumoral hemorrhage is rare. The mural nodule of a PXA shows moderate to intense enhancement on CECT. MR findings are similar to PA;  Over 90% of PXAs abut the pia and may incite reactive thickening of the adjacent dura . A " dural tail" sign was seen in 15-50% of cases in reported series. Large,more heterogeneous-appearing masses are typical of  aPXA  and leptomeningeal spread is more common with anaplastic variety.

24.   Diffuse Astrocytomas

25. Diffuse Astrocytoma, IDH-Mutant diffusely infiltrating WHO grade II astrocytoma. IDH-mutant DAs tend to grow slowly but have an intrinsic tendency for malignant progression to IDH mutant anaplastic astrocytoma (AA) and (eventually) IDH-mutant glioblastoma (GBM). can arise anywhere, the cerebral hemispheres are the most common site with a preferential location in the frontal lobes

26. The mean age at presentation is mid-30s (range 20 to 50 years) All diffuse astrocytomas are infiltrating lesions with ill defined borders. Gray-white matter interfaces are blurred Occasional cysts and calcification may be present. Hemorrhage is rare. CT Findings.   NECT shows an ill-defined homogeneous mass that is  hypodense relative to white matter . CECT shows no enhancement.

27. MR Findings: hypointense on T1WI  hyperintense on T2/FLAIR  although diffusely infiltrating astrocytomas  may appear somewhat circumscribed on MR, neoplastic cells generally infiltrate adjacent normal-appearing brain. T2* scans may show "blooming" foci if calcification is present. Doesn’t enhance and doesn’t restrict.

28. MRS shows elevated choline, low NAA, and a high mI:Cr ratio. 3T MRS may exhibit an elevated 2-hydroxyglutarate peak (2-HG) resonating at 2.25 ppm.

29. Anaplastic Astrocytoma, IDH-Mutant a diffusely infiltrating WHO Grade III astrocytoma with anaplasia, significant proliferative activity and have an inherent tendency for malignant progression to IDH-mutant glioblastoma. most common site of IDH-mutant AA is the cerebral hemispheres , especially the frontal and temporal lobes. Involvement of the deep gray nuclei is common in larger lesions.

30. Imaging features and differential diagnosis of IDH-mutant AAs are similar to and generally indistinguishable from those of IDH-mutant diffuse  astrocytomas . The majority do not enhance on CECT. When present, enhancement is usually focal, patchy, poorly delineated, and heterogeneous.

31. Glioblastoma, IDH-Wild-Type GBM is the most common malignant brain tumor in adults. IDH-wild-type glioblastoma (GBM) is the most common and  most malignant of all astrocytomas , accounting for over 95% of GBMs. Three inherited cancer syndromes—namely  neurofibromatosis type 1  (NF1),   Li-Fraumeni , and   Turcot syndrome —are associated with IDH-wild-type GBMs.

32. IDH wild-type GBMs are distributed throughout the cerebral hemispheres.  They preferentially involve the subcortical and deep periventricular white matter , easily spreading across compact tracts such as the corpus callosum and corticospinal tracts.  Symmetric involvement of the corpus callosum is common, the so-called "butterfly glioma " pattern. The most frequent appearance is a reddish gray tumor "rind" surrounding a central necrotic core . Mass effect and peritumoral edema are marked.   Increased vascularity and intratumoral hemorrhage are common.

33. GBMs can occur at any age (including in neonates and infants), but peak age is 55-85 years. GBM is a relentless, progressive disease. Mean survival in patients with IDH-wild-type GBM is under 1 year. Imaging The vast majority of IDH-wild-type GBMs demonstrate a thick, irregular, enhancing "rind" of tumor surrounding a necrotic core . CT Findings.  hypodense central mass surrounded by an iso- to moderately hyperdense rim on NECT. Hemorrhage is common, but calcification is rare.  Marked mass effect and significant hypodense peritumoral edema are typical ancillary findings.

34. CECT shows strong but heterogeneous irregular rim enhancement  . Prominent vessels in highly vascular GBMs are seen as linear enhancing foci adjacent to the mass. T1WI shows a poorly marginated mass with mixed signal intensity. T2/FLAIR shows heterogeneous hyperintensity with indistinct tumor margins and extensive vasogenic edema. Necrosis, cysts, hemorrhage at various stages of evolution, fluid/debris levels, and " flow voids " from extensive neovascularity may be seen. T1 C+ shows strong but irregular ring enhancement  surrounding a central non enhancing core of necrotic tumor

35. Nodular, punctate, or patchy enhancing foci outside the main mass represent macroscopic tumor extension into adjacent structures. Most GBMs do not restrict on DWI MRS usually shows elevated choline, decreased NAA and mI , and a lipid/lactate peak resonating at 1.33 ppm.

36. Gliosarcoma GBM variant with areas of glial ( gliomatous ) and mesenchymal (sarcomatous) differentiation. The temporal lobe is the most common site Two gross phenotypes Meningioma-like with superficial location, relatively circumscribed GBM-like with deep location, necrotic center + hypervascular tumor rind

37. Pediatric Diffuse Gliomas frequently arise in the midline (pons, thalamus, and spinal cord). A newly defined entity that is characterized by midline location and mutations in the histone H3 gene includes tumors that were previously referred to as diffuse intrinsic pontine glioma (DIPG) and is now officially recognized as  diffuse midline glioma, H3 K27M-mutant . Pediatric BSGs are divided into two groups by location

38. The most common location is the pons (two-thirds of cases). These pontine gliomas are called  DIPGs  The second group of midline gliomas consists of focal, much less aggressive tumors that are confined predominately to the tectal plate/periaqueductal region and often remain stable over long periods of time.

39. Imaging DIPGs   expand and diffusely infiltrate the pons and have indistinct margins. hypointense on T1WI and hyperintense on T2/FLAIR. DIPGs often expand anteriorly, enfolding and sometimes almost completely engulfing the basilar artery. Foci of necrosis and even intratumoral  hemorrhage may be present. Most DIPGs show either no or relatively little patchy enhancement.

40. Tectal gliomas   are discrete, well-marginated lesions that focally enlarge the colliculi or midbrain tegmentum and often obstruct the cerebral aqueduct. They are iso- to hypointense on T1WI and hyperintense on T2/FLAIR Contrast enhancement is minimal or absent. Tectal gliomas are indolent lesions that typically remain stable in size over many years.

41. OLIGODENDROGLIOMA CANONICAL (GRADE II) ANAPLASTIC(GRADE III)

42. Oligodendroglioma, IDH-Mutant and 1p/19q Codeleted Also known as " canonical oligodendrogliomas" Most OGs arise between the ages of 35 and 55  OGs are typically solid, soft, "fleshy," cortical  based  masses Most OGs arise at the gray-white matter junction & majority (85-90%) are supratentorial. Calcification is frequent, and zones of cystic degeneration are common. 

43. Imaging sharply delineated masses that involve the cortex and subcortical white matter. hypodense on NECT scan & often peripheral and cortically based.  Focal gyral expansion with thinning and remodeling of the overlying calvaria is common. Coarse nodular or clumped calcification is seen in 70-90% of cases.  Gyriform Ca++ is very suggestive

44. hypointense relative to gray matter on T1WI.   heterogeneously hyperintense on T2/FLAIR. Vasogenic edema is uncommon.  Calcification is seen as "blooming" foci on T2* sequences. Many OGs do not enhance on T1 C+  Moderate heterogeneous enhancement is seen in approximately half of all cases.  OGs do not restrict on DWI.

45. Other cortically based, slow-growing tumors that typically present with seizures include  ganglioglioma  and   dysembryoplastic neuroepithelial tumor (DNET) . GANGLIOGLIOMA : " Cyst + nodular" configuration noted WHO grade I neoplasms POST CONSTRAST enhancement more common 

46. DNET: multilobulated, hypointense, bubbly cortical mass on T1 and hyperintense on T2. WHO grade I neoplasm T1 C+ - MAY SHOW HETEROGENOUS ENHANCEMENT  FLAIR – heterogenously hyperintense with hyperdense rim--  BRIGHT RIM SIGN 

47. oligo ganglioglioma        DNET MIDDLE AGED HYPODENSE LESION WITH CA+2  MAY / MAYNOT ENHANCE  CHILDREN &YOUNG ADULTS CYST+NODULE HETEROGENOUS INTENSE ENHANCEMENT OF NODULE  CHILDREN &YOUNG ADULTS BUBBLY TUMOR BRIGHT RIM SIGN ON FLAIR MAY SHOW HETEROGENOUS ENHANCEMENT 

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