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Imaging approach to Tumors of the Meninges
Tumor of the meninges, arising from arachnoid meningothelial cells called arachnoid cap cells ( intracranial, intradiploic, spinal or ectopic). Meningioma is the most common non-glial primary brain tumor and most common intracranial extraaxial neoplasm. In this presentation, we will be going through the imaging approach to meningioma, related tumors and close mimics.
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Imaging approach to Tumors of the Meninges
- 1. Tumors of theMeninges Presented by: Dr. Anish Dhakal Resident, MD Radiodiagnosis Kathmandu University School of Medical Sciences (KUSMS) 3rd December, 2025
- 2. Meninges The cranialmeninges consists of : Dura mater. Outer periosteal layer. Inner meningeal layer. Arachnoid mater. Translucent membrane attached to the innermost dural layer. Give rise to arachnoid granulations Pia mater Pachymeninges Dura Leptomeninges Arachnoid + Piamater
- 5. Falx isa sickle shaped fold of dura that forms an incomplete partition between the cerebral hemispheres Extends from crista galli to internal occipital protuberance where it joins the tentorium Posteroinferiorly, it gives triangular shape for SSS Tentorium cerebelli: Attached from posterior clinoid process runs along petrous ridge to internal occipital protruberance
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- 8. Meningioma (typical) 88-94%, Atypical Meningioma 5-7% and Anaplastic (Malignant) Meningioma 1-2% WHO Classification
- 9. Meningioma Tumor ofthe meninges, arising from arachnoid meningothelial cells called arachnoid cap cells ( intracranial, intradiploic, spinal or ectopic). Most common non-glial primary brain tumor Most common intracranial extraaxial neoplasm Although meningiomas are physically attached to the dura, they actually arise from arachnoid "cap" cells rather than from the dura itself. 15% to 20% of all primary brain tumors. Incidence- 2-3 per 1,00,000 population
- 10. Age/ Gender: Peak incidence:40 to 60 years Rare in children (often atypical location or histology) Female: Male = 2:1 to 4:1 Association with hereditary tumor syndrome eg NF 2 – occurs in younger and no gender predilection. When associated with NF- 2: 10 % multiple Other: schwannoma, ependymoma
- 11. Etiology Cytogenetic: Chromosome 22 Loss of tumor suppressor gene NF2 1st event monosomy occur in chromosome 22 in 72% 2nd hit theory- remaining single NF2 copy is mutated Result in inactivation of NF2 gene protein ‘Merlin’ • 1p and 14q deletions Non-NF2 Meningiomas. Number of other driver mutations, including TRAF7, NOTCH2, SMARCB1, and SMO (which modulates hedgehog pathway signaling), have been identified in 50% of meningiomas with wild-type NF2. Ionizing radiation is the only established environmental risk factor for meningioma. The dose-related time interval to tumor development varies from 20 to 40 years – a/w chr 7 monosomy.
- 12. Receptor activity Meningiomasare related to sex hormones Common in women (peaking at 3.5-4.0:1.0 in premenopausal women in the 35- to 44-year age group) Correlated positively with breast carcinoma Meningiomas sometimes increase in size during pregnancy. Progesterone and possibly estrogen receptors have been demonstrated in many meningiomas . Radiation therapy appears to be a predisposing factor in the development of some meningiomas
- 13. About 96% ofmeningiomas occur within the skull: Intracranial Supratentorial location is the most common: 90% Infratentorial location: 8-10% (most common in in CPA) LOCATIONS OF MENINGIOMA Among extracranial location, PNS is the most common site
- 14. Size andNumber: Meningiomas vary widely in size. Most are small (<1 cm) and found incidentally at imaging or autopsy. Some, especially those arising in the anterior fossa from the olfactory groove attain large size before causing symptoms. Meningiomas can be solitary (90%) or multiple. Multiple meningiomas occur in NF2 as well as in multiple meningiomatosis syndrome.
- 15. WHO division ofmeningiomas Grade I – Typical meningiomas. Typical meningiomas account for 90-95% of these tumors. Grade II – Atypical meningiomas. Also includes clear cell and choroid tumors. Grade III – Anaplastic/malignant meningiomas. Also includes papillary and rhabdoid tumors.
- 16. Pathology: Gross GLOBOSE: Spherical/lobulatedmass Sharply circumscribed lesions with a well delineated tumor brain interface. EN PLAQUE: • Flatter sheet like extension covering the dura that infiltrates dura: dural thickening. • Sometimes invades underlying bone. • No parenchymal invagination Necrotic and hemorrhagic foci: often present, gross hemorrhage is uncommon (1-2%). Cystic/ xanthomatous changes may be present. A “collar” of reactive thickened dura often surrounds the meningioma base. A distinct “cleft” of arachnoid with trapped CSF and prominent vessels that surround the extraaxial mass is often observed.
- 17. Commonly invadeadjacent dural venous sinuses, may extend through the dura to involve the skull inducing calvarial hyperostosis. Although small “microcysts” are not uncommon in TMs, gross cystic change is rare. Frank hemorrhage is uncommon, occurring in only 1-2% of cases. Rarely, metastasis from an extracranial primary to an intracranial meningioma occurs (collision tumors) are typically lung or breast metastases to a histologically benign meningioma. The vast majority of meningiomas (90-95%) are benign WHO grade I tumors and, by definition, carry a low risk of recurrence and aggressive growth. Their mitotic index is low with MIB-1 usually <1%. Histologically benign-appearing meningiomas that show gross or microscopic brain invasion are designated as grade II neoplasms.
- 18. Clinical presentation: Lessthan 10% cause symptoms Clinical presentation vary with location Convexity or parasagittal tumors -Seizure and hemiparesis is common presentation Basisphenoid lesions usually present as visual field defects. Cavernous sinus meningioma associated with multiple cranial nerve palsies. Frontal meningioma often become very large before causing symptoms other than anosmia.
- 19. Treatment Options:Stratified treatment risk: benefit ratios vary, not just with tumor type, grade, and methylation status, but also with size and location, vascular supply, and presence or absence of a brain/tumor cleavage plane. Image-guided surgery with resection of symptomatic lesions is generally curative. The major factor associated with meningioma recurrence is subtotal resection.
- 20. Imaging Plain filmradiography Hyperostosis Erosion Enlarged vascular channels Tumor calcifications Pneumosinus dilatans Plain radiography of meningioma. Frontal (a) and lateral (b) views of the skull demonstrate hyperostosis of the left greater and lesser sphenoid wings (H), enlarged meningeal artery grooves (arrowheads), and calcium within the tumor (arrows).
- 21. CT SCAN: Plain andCECT detect 85% and 95% intracranial meningioma NECT: Typically show sharply circumscribed round or smoothly lobulated mass that abuts a dural surface, usually at obtuse angle. • Hyperdense to normal brain: 70- 75% • Isodense (25%), Hypodense(1-5 %), fat density in lipoblastic • Calcification: 20- 25 % • Necrosis/cyst: 8-23 % • Hemorrhage : Rare • Peritumoral edema: 60% • Bone window: Hyperostosis, irregular cortex, increased vascular markings. Hyperostosis can be associated with
- 23. MRI • Exhibit typicalfeatures of extra axial tumors. The majority of meningiomas are isointense with cortex on all sequences. Between 10-25% of cases demonstrate change suggestive of cyst formation or necrosis, although frank hemorrhage is uncommon. • Superior to CT in assessing: 1. Vascular encasement, particularly ICA in lesions around skull base. 2. Patency of venous sinuses T1WI: Iso- to slightly hypointense compared to cortex. Predominant hypointensity on T1WI and hyperintensity on T2WI suggest the microcystic variant. T2W: Most meningiomas are iso- to moderately hyperintense compared with cortex on T2WIs. T2-/FLAIR-hypointense tumors tend to be “hard” and somewhat gritty. Densely fibrotic and calcified meningiomas (appearing as “brain rocks” on NECT) can be very
- 24. Meningioma-associated cystsare found in 4-7% of cases. These can be intra- or extra-/peritumoral. The CSF-vascular “cleft” is especially well delineated on T2WI and is seen as a hyperintense rim interposed between the tumor and brain. A number of “flow voids” representing displaced vessels are often seen within the “cleft.” Sometimes a “sunburst” pattern that represents the dural vascular supply to the tumor can be identified radiating toward the periphery of the mass
- 25. FLAIR: Meningiomasignal intensity varies from iso- to hyperintense relative to brain. FLAIR is especially useful for depicting peritumoral edema, which is found with 1/2 of ∼ all meningiomas. Peritumoral edema is related to the presence of pial blood supply and VEGF expression, not tumor size or grade. Pools of CSF trapped in the cleft between tumor and brain (nonneoplastic “peritumoral cysts”) are usually proteinaceous and may not suppress completely on FLAIR. T1 C+: Virtually all meningiomas, including densely calcified “brain rocks” and intraosseous tumors, demonstrate at least some enhancement following contrast administration. Over 95% enhance strongly and homogeneously.
- 26. A dural“tail” is seen in the majority of meningiomas and varies from a relatively focal area adjacent to the tumor to dural thickening and enhancement that extends far beyond the site of tumor attachment. The dural “tail” often enhances more intensely and more uniformly than the tumor itself. “Dural tail” sign is not pathognomonic of meningioma. Most of the enhancing dural “tail” represents benign, reactive dural thickening. Tumor extending 1 cm beyond the base of the tumor is rare. Nonneoplastic peritumoral cysts do not enhance. Enhancement around the rim of a cyst suggests the presence of marginal tumor in the cyst wall, so complete cyst resection is recommended if technically feasible. Axial TI WI C+ MR shows a dural-based extraaxial mass in the left frontal lobe with intense enhancement and dural "tail" . Note the trapped pools of CSF around the tumor.
- 31. Typical meningioma Akacommon meningioma Meningiomas can be solitary (90%) or multiple. Meningiomas have two general configurations: a round ("globose") and a flat, sheet-like or carpet-like ("en plaque") appearance Meningioma variants include benign histologic subtypes such as meningothelial, fibrous, transitional, psammomatous, microcystic, secretory, and angiomatous meningiomas. All of these variants are classified as WHO grade I neoplasms. Most WHO grade I meningiomas have progesterone receptors, and progesterone receptor expression is inversely associated with meningioma grade.
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- 36. CT ANGIOGRAPHY: • Delineatesarterial supply, venous drainage • DSA - "Sunburst“ or radial appearance: Dural vessels supply lesion core , - Pial vessels may be parasitized, supply periphery - En plaque meningioma is poorly vascularized. - Prolonged vascular "stain“: Mother in law sign-contrast material shows up early and stays till late in the venous phase. - Venous phase vital to evaluate sinus involvement • Interventional: Preoperative embolization - Decreases operative time and blood loss - Optimal interval between embolization and surgery is 7-9 days - Particulate agents (e.g., polyvinyl alcohol) - allows for greatest tumor softening alleviate resection of tumor
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- 39. A prolongedvascular “blush” that persists late into the venous phase is typical. In some cases, arteriovenous shunting with the appearance of “early draining” veins occurs
- 40. Other Sequencesin MRI: T2* sequences: Helpful to depict intratumoral calcification. “Blooming” secondary to intratumoral hemorrhage is rare. Most meningiomas do not restrict on DWI. Perfusion MR may be helpful in distinguishing TM from atypical/malignant meningiomas. High rCBV in the lesion or in the surrounding edema suggests a more aggressive tumor grade.
- 41. MR spectroscopy inmeningioma • Alanine: Elevated double or triple peak at 1.3- 1.5 ppm • Alanine (Ala, peak at 1.48 ppm) is often elevated in meningioma, although glutamate-glutamine (Glx, peak at 2.1-2.6 ppm) and glutathione (GSH, peak at 2.95 ppm) may be more specific potential markers. • Cho peak: Average or slightly high. Choline reflects membrane turnover and correlates with malignancy. • Cr: Very low or absent • NAA: Absent or very low implies to non neuronal origin of mass. • Variable amounts of lactate.
- 42. The majordifferential diagnosis of typical meningioma is atypical or malignant meningioma. There are no pathognomonic imaging features that reliably distinguish benign meningioma from these more aggressive variants, but WHO grade I lesions are statistically far more common. Malignant meningiomas typically invade the brain and may exhibit a “mushrooming” configuration. Dural metastasis, usually from a breast or lung primary, may be virtually indistinguishable from meningioma on imaging studies. Other meningioma mimics include granuloma (TB, sarcoid) and inflammatory pseudotumors. Neither has the intense vascularity of meningioma. Differential diagnosis
- 43. Rare entitiesthat can closely resemble meningioma include hemangioma and solitary fibrous tumor/hemangiopericytoma. A hemangioma of the dura or venous sinuses is a true vasoformative neoplasm that can resemble meningioma. Most hemangiomas are very hyperintense on T2WI, whereas most meningiomas are iso- to mildly hyperintense. Delayed slow centripetal “filling in” of the mass on dynamic contrast-enhanced MR is suggestive of hemangioma. Intracranial solitary fibrous tumor/hemangiopericytoma is relatively rare found adjacent to the dura and venous sinuses (may be indistinguishable on imaging studies from typical meningioma) Extramedullary hematopoiesis (EMH) can present as confluent or multifocal dura-based disease resembling “en plaque” solitary or multiple meningiomatosis. EMH occurs in the seeding of chronic anemia or marrow depletion disorders.
- 44. Atypical meningiomas Location -Arise from the calvaria. Gross Pathology - Approximately half of all atypical meningiomas invade the adjacent brain. Microscopic Features - The 2016 WHO now recognizes brain invasion together with a mitotic count of four or more mitoses per high-power field Epidemiology - AMs represent 10-15% of all meningiomas. Demographics - Occur in slightly younger patients compared with TMs. Pediatric meningiomas tend to be more aggressive. In contrast with TMs, AMs display a slight male predominance. Natural History - AMs are generally associated with a higher recurrence rate (25-30%). Atypical meningioma corresponds to WHO grade II. The most aggressive form of meningioma is anaplastic (“malignant”) meningioma. Anaplastic meningiomas are WHO grade III neoplasms.
- 45. Atypical meningiomas -Imaging CT Findings: AMs are usually hyperdense with irregular margins. Minimal or no calcification is seen, and frank bone invasion with osteolysis is common. MR Findings: Tumor margins are usually indistinct with no border between the tumor and the underlying cortex. A CSF- vascular "cleft" is often absent or partially effaced. Peritumoral edema and cyst formation are common but nonspecific finding. Contrast enhancement is strong but often quite heterogeneous. ADC is significantly lower in atypical and malignant meningiomas compared with TMs. Perfusion MR may show elevated rCBV, especially in the peritumoral edema. MRS often shows elevated alanine.
- 48. Differential diagnosis: Atypical meningiomas Because it is difficult to determine meningioma tumor grade on the basis of imaging findings alone, the major differential diagnosis of AM is meningioma, WHO grade I. Dural metastasis and malignant meningioma can also be indistinguishable from AM. Sarcomas may also be difficult to distinguish from biologically aggressive meningiomas.
- 49. Anaplastic meningiomas Most anaplasticmeningiomas invade the brain and exhibit histologic features of frank malignancy. These include increased cellular atypia with bizarre nuclei and markedly elevated mitotic index (more than 20 mitoses per 10 high- power fields). Epidemiology - Frankly malignant meningiomas are rare, representing only 1-3% of all meningiomas. Malignant meningiomas have a striking male predominance. Natural History - Prognosis is poor. Recurrence rates following tumor resection range from 50-95%. Survival times range from 2-5 years and vary depending on resection extent.
- 50. Imaging: General Features -The imaging triad of extracranial mass, osteolysis and "mushrooming" intracranial tumor is present in most but not all cases of anaplastic meningioma. Calcification is rare, and contrast enhancement is typically heterogeneous. FLAIR: Marked peritumoral edema DWI: Restricted diffusion T1+C: Intense enhancement D/D – Anaplastic meningiomas, SFT, sarcomas, mets
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- 54. Differential diagnosis Atypicalmeningioma can be indistinguishable from malignant meningioma on imaging studies alone, as brain invasion occurs in both. The other major differential diagnosis of anaplastic meningioma is duraarachnoid metastasis. Rare tumors, such as solitary fibrous tumor (hemangiopericytoma), and sarcomas, such as meningeal fibrosarcoma, can all mimic anaplastic meningioma.
- 55. Suprasellar meningioma 10%of all intracranial meningiomas. Origin: From arachnoid +dura along tuberculum sellae/clinoids/diaphrag matic sellae/cavernous sinus with sec. extension into sella Irregular hyperstosis – blistering adjacent to sinus (hallmark of meningiomas at planum sphenoidale/tuberculum sellae) Suprasellar meningioma; Sagittal T1-weighted post- gadolinium MRI. A lobulated, enhancing suprasellar mass arises from the region of the tuberculum sellae and extends down into the pituitary fossa displacing the pituitary stalk posteriorly. Enhancing dural ‘tails’ (arrowheads) can be seen extending over the planum sphenoidale and clivus.
- 56. Intraventricular Meningioma Arises from Arachnoidcells of tela choroidea Cell rest within stroma of the choriod plexus. 0.7% of all meningioma, 30-60 yrs , F:M- 2:1 Pediatrics- 1/5 of meningioma arise from ventricles ( NF-II) Trigone of lateral ventricle is the most common site
- 57. 50-year-old female patientwith intraventricular meningioma in the left trigonum. • Peripheral calcification (A) and homogeneous contrast uptake (B) can be seen on NECT and CECT, respectively • Shows restricted diffusion (C)
- 58. Meningiomas Differences TM ATM/AM 1.Demographics More common Less common/rare 2. Sex Female predominance (2:1) More in males 3. Imaging Features Well-defined, calcifications in about 25%, homogeneous enhancement, no flow voids Irregular, no calcifications, heterogeneous enhancement, flow voids present 4. Brain Invasion Absent, CSF cleft present Present, CSF cleft absent 5. Skull Invasion Absent, Hyperostosis present Present, Osteolysis present 6. Perfusion MR Relatively less flow More flow 7. MRS and ADC GGG rise Alanine rise, Low ADC values. 8. Histology Mitotic count low per HPF High mitotic count per HPF.
- 59. Nonmenigotheliomatous tumors Nonmeningothelialtumors rarely involve the CNS. When they do, they are usually extraaxial lesions that correspond to soft tissue or bone tumors found elsewhere in the body. Both benign and malignant varieties of each type occur, ranging from benign (WHO grade I) to highly malignant (WHO grade IV) sarcomatous neoplasms. Most maligannt ones are sarcomas: Angiosarcoma, chondrosarcoma, fibrosarcoma,Osteosarcoma, rhabdomyosarcoma, Meningeal sarcoma, Ewing sarcoma
- 60. Benign Tumors (BMTs) With the exception of hemangiomas and lipomas, cranial nonmeningothelial tumors are all rare. Together, these BMTs account for <1% of all intracranial neoplasms. Overall, chondroma/enchondroma is the most common benign osteocartilaginous tumor of the skull base Osteoma is the most common benign osseous tumor of the calvarium.
- 61. Solitary fibroustumors (SFTs) can arise anywhere but are generally dura based. Osteomas are benign tumors that arise from membranous bone. In the head, the paranasal sinuses and calvarium are the most common sites. Most BMTs occur as solitary nonsyndromic lesions. Multiple BMTs generally occur as part of inherited tumor syndromes. Multiple osteomas occur as part of Gardner syndrome (together with skin tumors and colon polyps). Multiple enchondromas or “enchondromatosis” are part of Ollier disease. Enchondromas associated with soft tissue hemangiomas are found in Maffucci syndrome. Imaging findings vary with tumor type. Most BMTs are benign appearing nonaggressive masses of the scalp, skull, or dura that resemble their counterparts found elsewhere in the body.
- 62. Malignant Mesenchymal Tumors MMTs are rare tumors. In the aggregate, they represent 0.5- 2.0% of intracranial neoplasms. Most MMTs are sarcomas (of many histologic types) and other neoplasms, such as undifferentiated pleomorphic sarcoma/malignant fibrous histiocytoma (MFH). Most are WHO grade IV neoplasms. Most intracranial MMTs arise in the dura or skull base. Some arise in the scalp or calvarium. Chondrosarcomas classically arise from the petrooccipital fissure. Imaging findings of MMTs are those of highly aggressive dural, skull base, calvarial, or scalp lesions that invade adjacent structures
- 63. NECT scansshow a mixed- density soft tissue mass that causes lysis of adjacent bone. Chondrosarcoma may have stippled calcifications or classic “rings and arcs.” Sometimes “sunburst” calcifications can be seen in osteosarcomas. Periosteal reaction is generally absent with the exception of Ewing sarcoma.
- 64. Other thansuggesting a highly aggressive mass, there are no MR findings specific for MMTs. Fibrous, chondroid, and osteoid tissue are often very hypointense on both T1- and T2WI. FLAIR is very helpful in demonstrating brain invasion. Most MMTs enhance strongly but heterogeneously. Foci of necrosis are common. There are no characteristic radiologic findings that distinguish most MMTs from other aggressive neoplasms, such as malignant meningioma or metastases. Sarcoma subtypes are difficult to identify on the basis of imaging findings alone. For example, a histologically definite liposarcoma may demonstrate virtually no imaging features that would suggest the presence of fat.
- 66. Hemangiomas Location - Intracranialhemangiomas can be located in different cranial compartments but are almost always extraaxial. They are found in the calvarium, dural venous sinuses and dura. Microscopic Features - Hemangiomas are classified on the basis of their dominant vessels and can be capillary, cavernous, or mixed lesions. Most intracranial hemangiomas are cavernous. Demographics - Hemangiomas can occur at any age although the peak presentation is between the fourth and fifth decades. The M:F ratio is 1:2-4.
- 67. Scalp hemangiomaspresenting with Kasabach-Merritt syndrome (consumptive coagulopathy due to sequestration and destruction of clotting factors within the lesion, thrombocytopenia and hemangiomas – triad). Intracranial hemangiomas occasionally occur as part of POEMS syndrome, a rare multisystem disease with typical features of polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma-proliferative disorders and skin changes.
- 68. Hemangiomas CT Findings:Bone CT shows that the inner and outer tables are thinned but usually intact. A thin sclerotic margin may surround the lesion. "Spoke-wheel" or reticulated hyperdensities caused by fewer but thicker trabeculae are present within the hemangioma, giving it a "honeycomb" or "jail bars" appearance. MR Findings: Mixed hypo- to isointensity is the dominant pattern on T1WI. Scattered hyperintensities usually are caused by fat—not hemorrhage— within the lesion. Most hemangiomas are markedly hyperintense on T2WI. Contrast-enhanced scans show diffuse intense enhancement. Dynamic scans show slow centripetal "filling in" of the lesion
- 74. Hemangiomas – D/D DifferentiationMeningiomas Hemangiomas Location Supratentorial - para- sagittal, convexal and sphenoid ridge Calvarium, dural or dural sinusal Prevalence More common Less common T2 Hyperintensity Present, Less marked Marked Contrast CT/MR Homogeneous enhancement Progressive fill in
- 75. Solitary fibrous tumor/hemangiopericytoma Location- Most SFT/HPCs are dura based, usually arising from the falx or tentorium. The most common site is the occipital region, where they often straddle the transverse sinus. Intraparenchymal SFT/HPCs occur in the cerebrum and spinal cord, often without a discernible dural attachment. The cerebral ventricles are another common site. Size and Number - SFT/HPCs are almost always solitary lesions. They are relatively large tumors, reaching up to 10 cm in diameter. Lesions more than 4-5 cm are not uncommon. Gross Pathology - SFTs are solid, lobulated, relatively well- demarcated neoplasms. HPCs contain abundant vascular spaces. Intratumoral hemorrhage is common.
- 76. Solitary fibrous tumor/hemangiopericytoma CT Findings:HPCs are hyperdense extraaxial masses that invade and destroy bone. Extracalvarial extension under the scalp is common. MR Findings: • Low-grade intracranial SFTs are circumscribed masses that are usually dura-based and resemble meningioma. Lesions are isointense with gray matter on T1WI and have variable signal intensity on T2WI. A mixed hyper- and hypointense pattern is common. • Most HPCs demonstrate mixed signal intensity on all sequences. They tend to be predominantly isointense to gray matter on T1 scans and iso- to hyperintense on T2 scans. Prominent "flow voids" are almost always present.
- 80. The majordifferential diagnosis of low-grade SFT is typical (WHO grade I) meningioma. The major differential of HPC is a highly vascular aggressive meningioma, particularly an atypical or malignant meningioma. HPCs rarely calcify or cause hyperostosis, and a “dural tail” sign is typically absent. Dural metastases with skull invasion can be indistinguishable from HPC. Uncommon neoplasms that can resemble HPC include gliosarcoma and malignant mesenchymal tumors. Rarely, an intracranial SFT/HPC or malignant mesenchymal tumor can cause severe hypophosphatemia and metabolic bone disease not explained by any other metabolic or hereditary disease. These osteomalacia-inducing tumors (OITs) can be confused with aggressive meningioma.
- 81. Solitary fibrous tumor– D/D Differentiation Meningiomas SFN 1. Occurrence/Size More common, relatively smaller Less common, larger 2. Location Supratentorial, dural based Dural based, occipital region 3. CT Findings Hyperdense with calcifications Hyperdense without calcification 4. MR Findings T1 – iso, T2 – Hyper and Homogeneous CE. No foci of hemorrhage and no flow voids T1 – iso, T2 – hypo Heterogeneous CE Foci of hemorrhage and hence flow voids. 5. Hyperostosis of the calvaria Present Absent, Invasion present 6. Dural tail Present Absent 7. Calcifications Present Absent
- 82. Hemangiopericytoma WHO classifiedas a tumor of uncertain origin. Subtype of angioblastic meningioma. Highly cellular and vascularized tumor – nearly always attached to dura Arises from modified pericapillary smooth muscle cells. Age 30-50 yrs Slight male preponderance. Grossly resembles meningioma, richly vascularized tumors with numerous penetrating blood vessels. High local recurrence rate50-90% Predilection for late distant metastasis particularly to lungs and bone.
- 83. Imaging appearance similarto meningiomas. • Multilobulated, narrow/ broad base of dural attachment. • Location: supratentorial occipital region • Cystic changes and necrosis common • Bone destruction is common. • Calcification and hyperstosis are not common features. • CT- Heterogeneous lesion on both pre and post contrast studies due to low density cystic or necrotic areas. • Enhancement is typically strong but inhomogeneous.
- 84. MRI: T1W: Isointense-heterogeneous T2W: Extensivesurrounding edema+ flow voids T1C+: Marked heterogeneous enhancement Dural tail in 50% Axial T2WI MR shows a large, heterogeneous occipital mass with flow voids and calvarial erosion ~ characteristic of hemangiopericytoma. (Right) Axial T1WI C+ MR in the same patient shows a lobular, heterogeneously enhancing extraaxial mass with central low signal likely related to necrosis. Hemangiopericytomas are typically attached to the falx, tentorium, or dural sinuses. These rare tumors have a high rate of recurrence and often metastasize outside the CNS.
- 85. Hemangioblastoma Aka capillaryhemangioblastoma Hemangioblastoma (HGBL) are benign, slow-growing, relatively indolent vascular neoplasms. HGBL occurs in both sporadic and multiple forms. Multiple HGBLs are almost always associated with the autosomal dominant inherited cancer syndrome, von Hippel-Lindau disease (VHL). A rare non-VHL form of multiple disseminated HGBLs is termed leptomeningeal hemangioblastomatosis VHL mutations (losses or inactivations) are present in 20-50% of sporadic HGBLs. Multiple key angiogenic pathways (including VEGF/VEGFR2 and Notch/DII4) are massively activated in HGBL and contribute synergistically to the tumor’s abundant vascularization.
- 86. It isthe second most common infratentorial parenchymal mass in adults (after metastasis). HGBLs can occur in any part of the CNS, although the vast majority (90-95%) of intracranial HGBLs are located in the posterior fossa. The cerebellum is by far the most common site (80%) followed by the vermis (15%). Approximately 5% occur in the brainstem, usually the medulla. The nodule of an HGBL is superficially located and typically abuts a pial surface Supratentorial tumors are rare, accounting for 5-10% of all HGBLs. Most are clustered around the optic pathways and occur in the setting of VHL.
- 87. Hemangiomas varyin size from tiny to large, especially when associated with a cyst. Unless they are syndromic, HGBLs are solitary lesions. If more than one HGBL is present, the patient, by definition, has VHL. Multiple HGBLs, positive family history, or presence of other VHL markers (such as visceral cysts, retinal angioma, renal cell carcinoma) should prompt genetic screening. Headache is the presenting symptom in 85% of cases. HGBLs produce erythropoietin, which causes secondary polycythemia in 5% of patients. ∼
- 88. Gross Pathology.The common appearance is that of a beefy red, vascular-appearing nodule that abuts a pial surface. A variably sized cyst is present in 50-60% of cases. Cyst fluid is typically yellowish, and the cyst wall is usually smooth. Approximately 40% of HGBLs are solid tumors. Microscopic Features. The cyst wall of most HGBLs is nonneoplastic and composed of compressed brain. Cyst formation in HGBLs is a result of vascular leakage from tumor vessels, not tumor liquefaction, necrosis, or active secretion. Mitoses in HGBLs are few or absent (MIB-1 usually < 1). HGBL is a WHO grade I neoplasm. There is no recognized atypical or anaplastic variant.
- 89. HGBLs exhibita “stuttering” growth pattern, they are frequently stable lesions that can remain asymptomatic for long intervals. Imaging progression alone is not an indication for treatment, although tumor/cyst growth rates can be used to predict symptom formation and future need for treatment. Although HGBLs show no intrinsic tendency to metastasize, there are sporadic reports of intraspinal dissemination. Complete en bloc resection is the procedure of choice. Total resection eliminates tumor recurrence, although new HGBLs may develop in the setting of VHL.
- 90. Imaging General Features.HGBLs have four basic imaging patterns: (1) Solid HGBLs without associated cysts, (2) HGBLs with intratumoral cysts, (3) HGBLs with peritumoral cysts (nonneoplastic cyst with solid tumor nodule), and (4) HGBLs associated with both peri- and intratumoral cysts (nonneoplastic cyst with cysts in the tumor nodule). A nonneoplastic peritumoral cyst with solid nodule is the most common pattern, seen in 50- 65% of cases. The second most common pattern is the solid form, seen in 40% of cases. ∼
- 91. CT Findings: Themost common appearance is a well delineated iso- to slightly hyperdense nodule associated with a hypodense cyst. Calcification and gross hemorrhage are absent. The nodule enhances strongly and uniformly following contrast administration.
- 92. MR Findings.An isointense nodule with prominent “flow voids” is seen on T1WI. If an associated peritumoral cyst is present, it is typically hypointense to parenchyma on T1WI but hyperintense compared with CSF
- 94. Compared withbrain parenchyma, the tumor nodule of an HGBL is moderately hyperintense on T2WI and FLAIR. Intratumoral cysts and prominent “flow voids” are common. The cyst fluid is very hyperintense on T2WI and FLAIR. Occasionally, an HGBL hemorrhages. If present, blood products “bloom” on T2*. Intense enhancement of the nodule—but not the cyst itself—is typical. Cyst wall enhancement should raise the possibility of tumor involvement, as compressed, nonneoplastic brain does not enhance. Noncystic HGBLs enhance strongly but often heterogeneously Multiple HGBLs are seen in VHL and vary from tiny punctate to large solid tumors
- 97. Supratentorial HGBLsare rare. Most occur around the optic nerves or chiasm. HGBL occasionally occurs as a hemispheric mass with a “cyst+nodule” appearance
- 98. Angiography: Themost common appearance is that of an intensely vascular tumor nodule that shows a prolonged vascular “blush”. “Early draining” veins are common. If a tumor-associated cyst is present, vessels appear displaced and “draped” around an avascular mass.
- 100. Differential diagnosis Thedifferential diagnosis of HGBL varies with age. In a middle-aged or older adult, the statistically most common cause of an enhancing posterior fossa intraaxial (parenchymal) mass is metastasis, not HGBL! DWI and DSC-PWI are helpful in the characterization and differentiation of HGBL from brain metastases. HGBL has higher minimum ADC values and relative ADC ratios compared with metastases. A cerebellar mass with “cyst + nodule” in a child or young adult is most likely a pilocytic astrocytoma, not HGBL or metastasis. Occasionally, a cavernous malformation can mimic an HGBL with hemorrhage.
- 101. References: Osborn's brain,Imaging, Pathology, and Anatomy, 2nd edition
- 102.
Editor's Notes
- #15 Neurofibromatosis – Types and Presentations.
- #16 Parasagittal meningioma with adjacent dural tail with compressed brain parenchyma
- #37 The cardinal angiographic findings are supplied from meningeal vessels and a dense, homogeneous, persistent blush. is not rare
- #44 ATM – Brain Invasion and Mitotic Count to classify as WHO Grade II.
- #45 VS TM – 1. Demography and Epidemiology. 2. Brain Invasion. 3. Skull Osteolysis. 4.Tumor Margins and Calcifications. 5. Flow Voids, Perfusion MR and MRS. 6. ADC/DWI. 7. Histology.
- #49 Triad of Anaplastic Meningioma.
- #57 Fig. 7.. The meningioma as well as increased choline and alanine levels on MRS (D). Note that the NAA peak is probably due to partial averaging by using a relatively large single-voxel proton resolved excitation spin echo sequence (PRESS) (E).
- #66 Are WHO Grade I Neoplasms.
- #75 Previously WHO (Grade I – SFT, Grade II – Hemangipericytomas and Grade III – Anaplastic Hemangiopericytomas).
- #81 D/D – Meningiomas (TM/ATM). Others are dural mets, malignant tumors and gliomas.
- #83 Axial CECT shows a heterogeneously enhancing mass in the occipital region with extensive bone erosion. Note the surrounding edema and mass effect. Location and appearance are typical of hemangiopericytoma.