CNS Flashcards
Lobulated brain tumour formed of meningothelial cells with ‘syncytial’ appearance (indistinct cell borders) and whorls of cells streaming in parallel. Cells have eosinophilic cytoplasm and small, oval, regular nuclei with fine powdery chromatin, often with nuclear pseudo inclusions. Psammoma bodies are another classic finding.
Meningothelial meningioma (WHO CNS Grade 1)
Differential diagnoses
Schwannoma
Solitary fibrous tumour
Plan:
Correlate with clinical history/radiology (?dural based)
Examine further blocks (for higher grade features)
IPX to support Dx: SSTR2a, EMA, PR
IPX to rule out DDx: STAT6, S100
Next steps - synoptic report and discuss at MDT
A meningioma in which the vascular component exceeds 50% of the total tumour area
Angiomatous meningioma (WHO CNS Grade 1)
Differential diagnosis:
Haemangioblastoma
Plan:
Correlate with clinical history/radiology (?dural based, haemangioblastoma is intraaxial)
Examine further blocks (for higher grade features)
IPX to support Dx: SSTR2a, EMA, PR
IPX to rule out DDx: Inhibin
Next steps: Synoptic report and discuss at MDT
Brain lesion with prominent perivascular lymphoid infiltrates, numerous macrophages
Multiple sclerosis
Differential diagnosis:
Infarct
Infective process
Other degenerative disorders (e.g ADEM, PML)
Plan:
Correlate with clinical history/radiology (?multiple enhancing white matter lesions)
Stains to confirm diagnosis:
Luxol fast blue (demonstrate demyelination)
CD68 (confirm macrophage nature of cells)
Stains to exclude differentials: Gram, PAS, GMS, ZN
Diffusely infiltrating, highly cellular brain tumour composed of poorly differentiated tumour cells with nuclear atypia and marked pleomorphism. Mitotic activity is brisk. Necrosis (typically ‘palisaded’) and microvascular proliferation (multilayered endothelia within vessels) is diagnostic.
Glioblastoma multiforme (WHO CNS Grade 4)
Differential diagnosis:
Astrocytoma, IDH mutant, WHO CNS Grade 4
Plan:
Correlate with clinical history/radiology (?sporadic intra-axial enhancing tumour)
IPX to support Dx: GFAP, S100, Olig2
IPX to rule out DDx: IDH1 mutant protein
Molecular testing:
ATRX and p53 immunostain
IDH1 gene testing if <65 y/o
Glioma gene panel
Next steps: Synoptic report and discuss at MDT
Brain tumour with round, monotonous nuclei with clear cytoplasm creating a fried egg appearance. The tumour forms a delicate ‘chicken wire’ vasculature. Cells are discohesive, often microcystic, and show satellitosis. Macrocalcifications are a common degenerative change.
Oligodendroglioma (WHO CNS Grade 2)
DDx:
Diffuse astrocytoma
Metastatic clear cell carcinoma
Clear cell meningioma
Demyelinating lesion (macrophages)
Plan:
Correlate with clinical history / radiology
Examine further blocks (for higher grade features)
IPX to support Dx: IDH1 mutant protein, GFAP, Olig2
IPX to disprove DDx: Pancytokeratin, SSTR2a, CD68
-Can also use p53 and ATRX to discount astrocytoma
Molecular testing: 1p/19q codeletion (must have), glioma gene panel
Next steps: Synoptic report, discuss at MDT
Brain tumour with abrupt interface. Cells have round or oval nuclei with speckled chromatin. Cells form perivascular anucleate zones (pseudorosettes), and in some cases make true rosettes (cells radially arranged around a lumen). Other common features are hyalinization of blood vessels and calcification.
Ependymoma (WHO CNS Grade 2)
Differential diagnosis:
Medulloblastoma (if posterior fossa)
Diffuse glioma
Meningioma
Schwannoma
Plan:
Correlate with clinical history/radiology
Examine further sections (e.g. for higher grade features)
IPX to support Dx: GFAP, S100, EMA (perinuclear dot like)
IPX to discount DDx: Synaptophysin, Olig2, IDH1 mutant protein
Molecular testing (depending on site)
Supratentorial - YAP1 / ZFTA fusion
Posterior fossa - DNA methylation profile
Spinal - MYCN amplification
Next steps: Synoptic report, discuss at MDT
Spinal tumour with glial cells arranged around hyalinized fibrovascular cores which show perivascular accumulation of myxoid material. Myxoid material can also accumulate in microcysts.
Myxopapillary ependymoma (WHO CNS Grade 2)
Plan:
Correlate with clinical history/radiology (?distal spinal cord location)
Next steps: Synoptic report, discuss at MDT
Brain with diffusely infiltrating glial cells, without cellular cohesion, generating a loose (often microcystic) fibrillary background. Cellularity is mildly to moderately increased with mild nuclear atypia and mitotic activity should be absent or uncommon.
Diffuse astrocytoma, (WHO CNS Grade 2)
Differential diagnosis:
Normal or reactive brain
Oligodendroglioma
Lymphoma
Plan:
Correlate with clinical history / radiology
Examine further sections (for higher grade features)
Stains to support Dx: GFAP, Olig2, IDH1 mutant protein, p53, ATRX (expect mutant / lost)
Stains to discount DDx: CD45, CD20
Molecular testing:
1p/19q codeletion, CDKN2A/2B, TERT, glioma gene panel
Next steps: Synoptic report, discuss at MDT
Brain lesion with cords, lobules, and whorls of squamous cells, which show central ‘stellate reticulum’ (loose, microcystic areas) and prominent peripheral palisading. The tumour produces areas of ghost cells / wet keratin, and there can be cysts, calcification, and granulomatous reaction. Adjacent brain shows piloid gliosis and Rosenthal fibers
Adamantinomatous craniopharyngioma (WHO CNS Grade 1)
Plan:
Correlate with clinical presentation / radiology (?cystic suprasellar mass)
IPX to support Dx: Beta catenin (expect nuclear/cytoplasmic positivity)
Next steps: Synoptic report, discuss at MDT
Well circumscribed brain tumour of clear/vacuolated lipid containing cells (neoplastic stromal cells) with abundant vascular network. Resembles renal cell carcinoma. Clear cell aggregates can induce extramedullary hematopoiesis
Haemangioblastoma (WHO CNS Grade 1)
Differential diagnosis:
Metastatic clear cell RCC
Clear cell meningioma
Paraganglioma
Plan:
Correlate with clinical history and radiologic features (?cerebellar ?VHL syndrome)
IPX to support Dx: Inhibin-alpha
IPX to discount DDx: AE1/AE3, PR and SSTR2a, synaptophysin and chromogranin
Next steps: Synoptic report, discuss at MDT
Advice to clinician: May be assiociated with VHL syndrome. Clinical correlation required
Circumscribed tumour with biphasic appearance - compact fibrillary portions and loose microcystic areas. Fibrillary areas have cells with bipolar (at both ends of cell) ‘piloid’ (hairlike) processes, and Rosenthal fibers. Looser microcystic areas show cobweb-like cell processes and eosinophilic granular bodies.
Pilocytic astrocytoma
(WHO CNS Grade 1)
Differential diagnosis: Reactive piloid gliosis
Plan:
Correlate with clinical history and radiologic features (?cystic tumour with enhancing mural nodule)
Examine further sections (e.g for anaplastic features)
IPX to support Dx: GFAP, S100, Olig2
Molecular (if available): BRAF fusion
Next steps: Synoptic report, discuss at MDT
