Neuropathology Evening Session: Case 3 Christine E. Fuller, MD Cincinnati Children s Hospital Medical Center Disclosure of Relevant Financial Relationships USCAP requires that all faculty in a position to influence or control the content of CME disclose any relevant financial relationship WITH COMMERCIAL INTERESTS which they or their spouse/partner have, or have had, within the past 12 months, which relates to the content of this educational activity and creates a conflict of interest. Dr. Christine Fuller declares she has no conflicts of interest to disclose. Clinical Presentation MRI findings T1 Post contrast 10 year-old girl presented with 2 month history of intermittent episodes of emesis She began experiencing episodes (<10 seconds) of panic attacks Decreased PO intake and weight loss; PCP referral to neurologist Panic attacks = seizures; appropriate imaging studies ordered Large confluent expansile mass centered within the right thalamus / basal ganglia and extending into the right temporal lobe Image 3A FLAIR FLAIR Image 3B 1
FSE / T2 She underwent subtotal resection / excisional biopsy of the lesion (right temporal lobe portion) Post-operative Keppra and dexamethasone Image 3C Image 3D Image 3E Ki67 Image 3F Image 3G 2
Additional tests MSAIPBTP Mutant- Specific Antibody Important in Pediatric Brain Tumor Pathology Image 3H Immunohistochemistry Olig2 - positive p53 - positive ATRX - retained nuclear staining IDH1 (R132H) - negative BRAF V600E negative MGMT promoter not methylated Array CGH 19.7 Mb single copy gain 2p 105.1 Mb single copy loss 17p Monosomy 14 and 18 Post-operative treatment radiation therapy with concurrent Temozolomide and Avastin Q2 weeks Avastin Q2 weeks and Temozolomide 5 days each 28 day cycle 7 months post-surgery she once again developed seizures, numbering up to 20 seizures in one 4 hour period MR imaging studies noted tumor progression, with overall increase in tumor involvement of the left cerebral hemisphere as well as posterior fossa structures Started on dexamethasone, keppra, and clobazam Transferred to CCHMC and was enrolled on PBTC043 Currently in the first cycle of treatment and is clinically stable What is your interpretation of the MRI studies? What is the pathologic diagnosis based on histology?? Based on IHC findings (Mutant-specific antibody important in pediatric brain tumor pathology)?????? Differential diagnosis based on neuroimaging? 3
Based on imaging findings (tumor arising in thalamus) - Diffuse glioma - Gliomatosis cerebri - Other astrocytic tumor (pilocytic / pilomyxoid) - CNS embryonal tumor / ATRT - Ependymoma or choroid plexus tumor Common peds tumors; typically different imaging findings What is the diagnosis based on histology? Differential Diagnosis - Diffuse astrocytoma (grade?) - Other astrocytic tumors (pilocytic / pilomyxoid), CNS embryonal tumor / ATRT, ependymoma or choroid plexus tumor - Gliomatosis cerebri *No longer an entity; 2016 WHO CNS Tumours defines as a growth pattern of exceptionally widespread involvement of the CNS that may be seen with ANY of the diffuse glioma subtypes* Infiltrative astrocytoma - Cytologic atypia - Mitotic activity - Necrosis and microvascular proliferation are absent ANAPLASTIC ASTROCYTOMA, WHO III 2016 WHO Classification Combined histological molecular classification Phenotype + Genotype Diagnosis based on mutant-specific IHC findings???? WHO 2016 4
H3 K27M Final Diagnosis: Diffuse midline glioma, H3 K27M-mutant Image 3H Diffuse Midline Glioma, H3 K27M WHO 2016- infiltrative midline high-grade glioma with predominantly astrocytic differentiation and a K27M mutation in either H3F3A or HIST1H3B/C Mainly children Locations Brainstem (DIPG) Thalamus Spinal Cord - Local / regional to more diffuse parenchymal infiltration (gliomatosis cerebri) - Leptomeningeal spread Diffuse Midline Glioma, H3 K27M WHO GRADE IV Poor prognosis WHO 2016 mitotic activity is present in most cases, BUT IS NOT NECESSARY FOR DIAGNOSIS; microvascular proliferation and necrosis MAY be seen Diffuse Midline Glioma, H3 K27M 5
Immunohistochemistry S100, Olig2, GFAP - Positive Synaptophysin +/- Chromogranin / NeuN - Negative Nuclear p53 (50%) ATRX loss (10%) H3 K27M mutation Lysine Methionine substitution H3F3A (H3.3) HIST1H3B or HIST1H3C (H3.1) DIPG 80% (H3.3 >>>H3.1) Thalamus - 50% Cord 56% Histones Compacting DNA strands (Nucleosome) PRC2 - polycomb repressive complex 2 PRC2 Gene regulation PRC2 Hypomethylation Sci. Signal. 08 Jan 2008: Vol. 1, Issue 1, pp. eg1 Nature Genetics 45, 587 589 (2013) Acta Neuropathol (2014) 128:743 753 Wu et al, Nature Genetics 2014 6
Korshunov et al. Acta Neuropathol 2015 Korshunov et al. Acta Neuropathol 2015 Midline location Assess H3 K27M IHC first! How do we work up a pediatric diffuse glioma?!?!?!? ADDITIONAL TESTING NEEDED Diffuse midline glioma, H3 K27M mutant Pediatric diffuse astrocytoma Idh1 codon 132 Idh2 codon 172 Acta Neuropathol (2016) 131:803 820 Chiang JC, Ellison DW. J Pathol. 2016 Oct 4 7
Additional testing to consider Immunohistochemistry IDH1 R132H Oligo- idh and 1p/19q p53 ATRX BRAF V600E FISH Histo high grade - CDKN2A deletion, PDGFRa and MYCN amplification, NTRK2 rearrangement Histo low grade: MYB, MYBL1, FGFR1, and MYBL1 rearrangements Sequencing- targeted (IDH, BRAF) or next gen panels But wait. H3 K27M may be found in midline gliomas with: giant cells epithelioid and rhabdoid cells PNET-like foci neuropil-like islands pilomyxoid features ependymal-like areas sarcomatous transformation ganglionic differentiation PXA-like areas. Brain Pathology 26 (2016) 569 580 Brain Pathology 26 (2016) 569 580 Kleinschmidt-DeMasters et al, Brain Pathol, 2016 H3 K27M mutation in gangliogliomas can be associated with poor prognosis Lessons Learned Diffuse midline glioma, H3 K27M New diagnostic entity in WHO 2016 Mainly children (rare adults) midline structures Diagnosis requires demonstration of K27M mutation (H3.3 or H3.1) Grade IV, irrespective of histologic grading (at least for now ) Prolonged survival?!? For pediatric diffuse gliomas arising in midline structures FIRST, asses H3 K27M mutant status If Negative for H3 K27M, proceed with additional molecular testing similar to that used for classifying adult diffuse gliomas H3 K27M for all midline glial / glioneuronal tumors?!?!?; peds and adults?!?!? 8
References 1. Bechet D et al. Specific detection of methionine 27 mutation in histone 3 variants (H3K27M) in fixed tissue from high-grade astrocytomas. Acta Neuropathol. 2014; 128: 733-41. 2. Bender S et al. Reduced H3K27me3 and DNA hypomethylation are major drivers of gene expression in K27M mutant pediatric high-grade gliomas. Cancer Cell. 2013; 24: 660-72. 3. Buczkowicz P et al. Genomic analysis of diffuse intrinsic pontine gliomas identifies three molecular subgroups and recurrent activating ACVR1 mutations. Nat Genet. 2014; 46: 451-6. 4. Castel D et al. Histone H3F3A and HIST1H3B K27M mutations define two subgroups of diffuse intrinsic pontine gliomas with different prognosis and phenotypes. Acta Neuropathol. 2015; 130: 815-27. 5. Hochart A et al. Long survival in a child with a mutated K27M-H3.3 pilocytic astrocytoma. Ann Clin Transl Neurol. 2015; 2: 439-43. 6. Joyon N et al. K27M mutation in H3F3A in ganglioglioma grade I with spontaneous malignant transformation extends the histopathological spectrum of the histone H3 oncogenic pathway. Neuropathol Appl Neurobiol. 2016. 7. Korshunov A et al. Integrated analysis of pediatric glioblastoma reveals a subset of biologically favorable tumors with associated molecular prognostic markers. Acta Neuropathol. 2015; 129: 669-78. 8. Orillac C et al. Pilocytic astrocytoma and glioneuronal tumor with histone H3 K27M mutation. Acta Neuropathol Commun. 2016; 4: 84. 9. Schwartzentruber J et al. Driver mutations in histone H3.3 and chromatic remodeling genes in paediatric glioblastoma. Nature. 2012; 482: 226-31. 10. Solomon DA et al. Diffuse Midline Gliomas with Histone H3-K27M Mutation: A Series of 47 Cases Assessing the Spectrum of Morphologic Variation and Associated Genetic Alterations. Brain Pathol. 2015. 11. Venneti S et al. Evaluation of histone 3 lysine 27 trimethylation (H3K27me3) and enhancer of Zest 2 (EZH2) in pediatric glial and glioneuronal tumors shows decreased H3K27me3 in H3F3A K27M mutant glioblastomas. Brain Pathol. 2013; 23: 558-64. 12. Wu G et al. Somatic histone H3 alterations in paediatric diffuse intrinsic pontine gliomas and non-brainstem glioblastomas. Nature Genetics. 2012; 44: 251-3. 13. World Health Organization Classification of Tumours of the Central Nervous System. Revised 4th Edition ed. Lyon, FRANCE: IARC Press, 2016. 9