NON-NEUROEPITHELIAL TUMORS

R.Rengarajan

WHO classification

• Tumors of the Sellar Region • Hematopoietic tumors • Germ Cell Tumors • Tumors of the Meninges • Non-menigothelial tumors of the meninges • Tumors of Cranial and Spinal Nerves • Local Extensions from Regional Tumors • Metastatic tumours • Unclassified Tumors • Cysts and Tumor-like Lesions

• Tumors of the Sellar Region – Pituitary adenoma – Pituitary carcinoma – Craniopharyngioma

• Hematopoietic tumors – Primary malignant lymphomas – Plasmacytoma – Granulocytic sarcoma – Others

• Germ Cell Tumors – Germinoma – Embryonal carcinoma – Yolk sac tumor (endodermal sinus tumor) – Choriocarcinoma – Teratoma – Mixed germ cell tumors

• Tumors of the Meninges – Meningioma • variants: meningothelial, fibrous (fibroblastic),

transitional (mixed), psammomatous, angiomatous, microcystic, secretory, clear cell, chordoid, lymphoplasmacyte-rich, and metaplastic subtypes

– Atypical meningioma – Anaplastic (malignant) meningioma

• Non-menigothelial tumors of the meninges – Benign Mesenchymal

• osteocartilaginous tumors • lipoma • fibrous histiocytoma • others

– Malignant Mesenchymal • chondrosarcoma • hemangiopericytoma • rhabdomyosarcoma • meningeal sarcomatosis • others

– Primary Melanocytic Lesions • diffuse melanosis • melanocytoma • maliganant melanoma

– variant meningeal melanomatosis

– Hemopoietic Neoplasms • malignant lymphoma • plasmactoma • granulocytic sarcoma

– Tumors of Uncertain Histogenesis - hemangioblastoma

• Tumors of Cranial and Spinal Nerves – Schwannoma (neurinoma, neurilemoma)

• cellular, plexiform, and melanotic subtypes

– Neurofibroma • circumscribed (solitary) neurofibroma • plexiform neurofibroma

– Malignant peripheral nerve sheath tumor (Malignant schwannoma) • epithelioid • divergent mesenchymal or epithelial differentiation • melanotic

• Local Extensions from Regional Tumors – Paraganglioma (chemodectoma) – Chordoma – Chondroma – Chondrosarcoma – Carcinoma

Primary CNS lymphoma

• Malignant primary CNS neoplasm composed of B lymphocytes

• Enhancing lesion(s) within basal ganglia, periventricular WM

• 90% supratentorial

• Frontal and parietal lobes most common

• Deep gray nuclei commonly affected

• Lesions cluster around ventricles, GM-WM junction

• Often involve, cross corpus callosum

• Frequently abut, extend along ependymal surfaces

• NECT• Hyperdense classically• May be isodense• +/- Hemorrhage, necrosis (immunocompromised)

• CECT• Common: Moderate, uniform (immunocompetent)• Less common: Ring (immunocompromised)• Rare: Nonenhancing (infiltrative, mimics white matter disease)

• MR Findings

• T1WI

• Immunocompetent: Homogeneous isointense/hypointense to cortex• Immunocompromised: Isointense/hypointense to cortex

– May be heterogeneous from hemorrhage, necrosis

• T2WI

• Immunocompetent: Homogeneous isointense/hypointense to cortex– Hypointensity related to high nuclear to cytoplasmic ratio

• Immunocompromised: Isointense/hypointense to cortex– May be heterogeneous from hemorrhage, necrosis– Ca++ may rarely be seen, usually after therapy

• Mild surrounding edema is typical

• FLAIR• Immunocompetent: Homogeneous isointense/hypointense to cortex• Immunocompromised: Isointense/hypointense• May be hyperintense• Mild surrounding edema is typical

• T2* GRE: May see blood products or calcium as areas of "blooming" (immunocompromised)

• DWI: Restricted diffusion, low ADC map reported

• T1 C+• Immunocompetent: Strong homogeneous enhancement• Immunocompromised: Peripheral enhancement with central necrosis or homogeneous enhancement• Nonenhancement extremely rare• Lymphomatous meningitis is typically related to systemic disease

• MRS• NAA decreased, Cho elevated• Lipid and lactate peaks reported

• MR perfusion: Early studies show increased rCBV

Angiocentric lymphoma

• Rare malignancy characterized by intravascular proliferation of lymphoid cells with a predilection for CNS and skin

• A form of non-Hodgkin lymphoma (NHL) characterized by angiotropic growth

• Multifocal abnormal T2 hyperintensity in deep WM, cortex or basal ganglia + enhancement

• Supratentorial (periventricular/deep WM, G-W junction)

• May involve basal ganglia (BG), midbrain

• NECT: Focal, bilateral asymmetric low density lesions inWM, cortex, or basal ganglia

• CECT: Variable (none to moderate)

• T1 WI• Multifocal hypointense lesions• May see blood products

• T2WI• 45% hyperintensities in deep WM (edema, gliosis)• 36% cortex hyperintensity, infarct-like lesions• May see hemorrhagic transformation

• T2* GRE: May see blood products "blooming“

• DWI: Diffusion restriction reported

• T1 C+• Variable enhancement: Linear, punctate, patchy, nodular, ring-like, gyriform, homogeneous• o Meningeal and/or dural enhancement

Germinoma• Morphologic homologues of germinal neoplasms arising in the gonads and

extragonadal sites

• Pineal region mass that "engulfs" the pineal gland

• Midline near the 3rd ventricle - 80-90% (Pineal region - 50-65%, Suprasellar - 25-35%, Basal ganglia and thalami - 5-10%)

NECT• Sharply circumscribed dense mass (hyperdense to GM)• Pineal: Mass drapes around posterior 3rd ventricle or "engulfs" pineal gland• Suprasellar: Retrochiasmatic, non-cystic, non -calcified• ± Hydrocephalus

CECT• Strong uniform enhancement, ± CSF seeding• Cystic/necrotic/hemorrhagic components not uncommon with larger germinomas

(especially in basal ganglia)

• T1Wl• Isointense or hyperintense to GM• Early cases may only show absent posterior pituitary bright spot

• T2Wl• Iso-to-hyperintense to GM (high nuclear:Cytoplasmic ratio)• Cystic or necrotic foci (high T2 signal)• Less common: Hypointense foci (hemorrhage)

• FLAIR: Slightly hyperintense to GM

• T2* GRE: Calcification, hemorrhage (rare)

• DWI: Restricted diffusion due to high cellularity

• T1 C+: Strong, homogeneous enhancement, ± CSF seeding, ± brain invasion

• MRS: inc Choline, dec NAA, ± lactate

Teratoma

• Tridermal mass originating from displaced embryonic tissue that is misenfolded

• Midline mass containing: Ca++, soft tissue, cysts, and fat

• Hugs midline, optic chiasm, pineal gland (Majority are supratentorial)

• NECT: Fat, soft tissue, Ca++, cystic attenuation

• CECT: Soft tissue components enhance

MR Findings

• T1WI: inc signal from fat, variable signal from Ca++

• T2WI: Soft tissue components iso- to hyperintense

• FLAIR: dec signal from cysts, inc signal from solid tissue

• T2* GRE: dec signal from Ca++

• T1 C+: Soft tissue enhancement

• MRS: inc lipid moieties on short echo

Embryonal carcinoma

• Malignant tumor composed of undifferentiated cells

• Heterogeneous pineal or suprasellar mass in adolescent

• Hugs midline as other CNS GCTs

• Typically well circumscribed or lobulated

• NECT – Heterogenous - Isoattenuating to hyperattenuating

• CECT - Enhancing, ± cysts, hemorrhage

T1WI• Hypointense to isointense to GM• T1 shortening due to protein, blood or fat

T2WI: Isointense to slightly hyperintense to GM

FLAIR• Hyperintense solid elements• ± Hydrocephalus

T2* GRE: Dephasing from hemorrhagic foci

DWI: ± Restriction within solid components

T1 C+: Heterogeneous enhancement, ± CSF spread

MRS: inc Choline, inc lipid and lactate, dec NAA

Meningioma

• WHO grade 1 Meningioma

• Dural-based enhancing mass w/cortical buckling & trapped CSF clefts/cortical vessels

• Supratentorial (90%): Para sagittal/convexity (45%), sphenoid ridge (15-20%), olfactory groove (5-10%), parasellar (5-10%)

• Infratentorial (8-10%): CPA most common

• Misc inside the dural: Intraventricular, optic nerve sheath, pineal region

• Misc outside the dura: Paranasal sinus (most common), nasal cavity, parotid, skin, calvarium

• NECT• Hyperostosis, irregular cortex, tumoral calcifications, inc vascular markings• Sharply circumscribed smooth mass abutting dura• Hyperdense (70-75%), iso- (25%), hypo- (1-5%)• Calcified (20-25%): Diffuse, focal, sandlike, sunburst, globular, rim• Necrosis, cysts, hemorrhage (8-23%)• Rare lipoblastic subtype • Brain cysts & trapped pools of CSF common• Peritumoral hypodense vasogenic edema (60%)

• CECT: > 90% enhance homogeneously & intensely

• CTA: May complement DSA in defining vascular supply to tumor & normal tissues from each feeder artery before embolization

• T1WI• Usually iso- to slightly hypointense with cortex• Necrosis, cysts, hemorrhage (8-23%)• Best to visualize gray matter "buckling“

• T2WI• Variable; sunburst pattern may be evident• Necrosis, cysts, hemorrhage (8-23%)• Best to visualize trapped hyperintense CSF clefts (80%) & vascular flow voids

(80%)

• FLAIR: Hyperintense peritumoral edema, dural "tail“

• T2* GRE: Best sensitivity for calcification

• DWI: DWI, ADC maps for CM variable in appearance

• T1 C+• > 95% enhance homogeneously & intensely• Dural "tail" (35-80% of cases ): Non-specific• En plaque: Sessile thickened enhancing dura

• MRV: Evaluate possible sinus involvement

• MRS• Elevated levels of Alanine at short TE

• Reported peak ranges from 1.3-1.5 ppm

• Perfusion MRI: Good correlation between volume transfer constant (K-trans) & histologic grade

Atypical and malignant meningioma

Common meningioma = WHO grade 1 meningiomaAtypical meningioma = WHO grade 2 meningiomaMalignant meningioma = WHO grade 3 meningioma

• Dural based lesion locally invasive with areas of necrosis & marked brain edema

• Occur anywhere along neuraxis

• AM: Para sagittal (44%), cerebral convexities (16%)

• NECT• Hyperdense w/minimal or no calcification• Marked perifocal edema & bone destruction• CT "Triad" of MM: Extracranial mass, osteolysis, & intracranial tumor

• CECT• Enhancing tumor mass• Prominent pannus or tumor, extending away from mass termed "mushrooming"

• T1WI• Indistinct tumor margins• Extending tumor interdigitating with brain

• FLAIR:Marked peritumoral edema

• DWI• Markedly hyperintense on DWI• Marked decrease in ADC• Correlates with histopathology

• T1 C+• Enhancing tumor mass• Plaque like & may extend into brain, skull, scalp

• MRV: Evaluate possible sinus involvement

• MRS - Elevated levels of Alanine at short TE• Reported peak ranges from 1.3-1.5 ppm

Hemangioblastoma

• Vascular neoplasm of uncertain histogenesis

• Adult with intra-axial posterior fossa mass with cyst, enhancing mural nodule abutting the pia

• 90-95% posterior fossa ( 80% cerebellar hemisphere )

• 60% cyst with mural nodule ( 40% solid )

• NECT – low density cyst with isodense mural nodule

• CECT – Nodule enhances intensely, Cyst wall doesn’t enhance

• CTA – may demostrate arterial feeders

T1 WI• Nodule isointense with brain• Cyst moderately hyperintense to CSF

T2 WI• Both nodule and cyst are hyperintense• Prominent flow voids in some cases

FLAIR• Both cyst and nodule hyperintense

T1 C+• Nodule enhances intensely• Solid enhancement pattern less common• Cyst wall enhancement very less common

• 20-40 % HGBL occur in VHL patients (multiple tumors)• With visceral cysts, RCC

Hemangiopericytoma

• Sarcoma related to neoplastic transformation of pericytes

• Lobular enhancing extra-axial mass with dural attachment +/- skull erosion

• Supratentorial – occipital region most common

• NECT – hyperdense extra-axial mass with surrounding edema, calvarial erosion

• CECT – strong heterogenous enhancement

No Ca++ or hyperostosis

• T1 WI• Heterogenous mass, isointense to gray matter

• T2 WI• Heterogenous isointense mass• Prominent flow voids are common• Surrounding edema, mass effect are common• Hydrocephalus

• T1 C+• Marked heterogenous enhancement• Dural tail seen in 50%

• MRV – occlusion of venous sinuses

• MRS – elevated myoinositol

• Local recurrence common, 50-80%

• Extracranial metastases common, up to 30%• Commonly liver, lungs, lymph nodes, bones

Staging, Grading or Classification Criteria• WHO grade II or III (anaplastic)

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