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Intracranial Extra-axial Cavernous Angioma of the Cerebellar Falx
PEER-REVIEW REPORTS
Intracranial Extra-axial Cavernous Angioma of the Cerebellar Falx Angelina Graziella Melone, Catia P. Delfinis, Emiliano Passacantilli, Jacopo Lenzi, Antonio Santoro
䡲 INTRODUCTION: Intracranial cavernous hemangiomas are benign vascular malformations that can be divided into intra-axial and extra-axial types. Extra-axial cavernous angiomas (or hemangiomas) are rare lesions; intracranially, they arise in relation to the dura mater or at a spinal level mimicking meningiomas. They are very rarely reported in the posterior cranial fossa. 䡲 CASE REPORT: The authors report a case of a cavernous angioma that occurred in the cerebellar falx of a 58-year-old man. The lesion was discovered during cranial computed tomography (CT) and magnetic resonance imaging (MRI) examinations. The patient underwent surgery with en-bloc removal of the tumor. No significant intraoperative bleeding or complications occurred during the postoperative course. 䡲 CONCLUSION: Intra-axial and extra-axial cavernous angiomas are histopathologically identical lesions, but by the radiological features, it is very difficult to distinguish the extra-axial cavernous angiomas from meningiomas, especially when dural tail sign and calcification are present.
INTRODUCTION Intracranial cavernous angiomas are usually intraparenchymal, extra-axial malformations and are relatively rare, accounting for only 0.4%–2% of all intracranial vascular malformations (3, 19, 37). They have very rarely been reported as the cause of subarachnoid hemorrhage, in contrast to the intra-axial type (6). In relation to their attachment to the dura, they mimic meninKey words 䡲 Cerebellar falx 䡲 Extra-axial cavernous angioma 䡲 Hemangioma 䡲 Intra-axial cavernous angioma Abbreviations and Acronyms CT: Computed tomography MRI: Magnetic resonance imaging From the Department of Neurological ScienceNeurosurgery, University “Sapienza,” Rome, Italy To whom correspondence should be addressed: Angelina Graziella Melone, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2010) 74, 4/5:501-504. DOI: 10.1016/j.wneu.2010.07.015 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2010 Elsevier Inc. All rights reserved.
giomas, although their radiologic features appear quite different from intra-axial cavernomas. On computed tomography (CT) scan, extra-axial cavernous angiomas are isodense or hyperdense masses, showing homogeneous contrast enhancement. On T2-weighted magnetic resonance imaging (MRI), intra-axial cavernous angiomas usually exhibit a multifocal hyperintense center surrounded by a hypointense rim resulting from the blood products at different stages of evolution inside; on T1-weighted imaging, they appear isointense. Differential diagnosis of meningiomas is difficult because extra-axial cavernous angiomas appear isointense or hypointense on T1-weighted images and isointense or mildly hyperintense on T2-weighted images, showing intense contrast enhancement (2); extra-axial cavernous angiomas may exhibit a dural tail sign and calcifications, two findings typical of meningiomas. Grossly, cavernous angiomas are typically multilobulated lesions dark red to blue in color that contain hemic products at various stages of evolution. Histologically, these lesions are characterized by vascular channels lined with fibroconnective tissue stroma. The histologic architecture of the
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component vessels resembles that of capillary telangiectasias, consisting of a single layer of endothelium and varying quantities of subendothelial fibrous stroma, with a distinct absence of smooth muscle and elastic fibers. Regardless of their location, cavernous malformations are identical on histology, immunohistochemistry, and electron microscopy (3). Extra-axial lesions usually arise in relation to the dura mater intracranially or at a spinal level (3). Most of these malformations are found in the middle cranial fossa at the level of the cavernous sinus (1-18) and only rarely are found in other dural locations outside the middle fossa, such as the convexity (14), the anterior cranial fossa (15), the cerebellopontine angle (16), and Meckel cave (8). A few lesions have been described in the sellar and suprasellar region (5, 7), at the level of the cranial nerves (9, 15), and in the internal auditory canal (22). Skull extension (36) and intraosseous lesions of the skull (12) have also been reported. A few cases have originated from the falx cerebri (19). An English literature review of the last 20 years of the PubMed and Cochrane Databases yielded no results for cavernous angioma of the cerebellar falx. We report the case of a 58-year-old man in whom a cavernous angioma of the cerebellar falx was found, paying particular attention to its neuroradiologic features. The lesion was successfully removed.
CASE REPORT A 58-year-old man experienced an episode of mental confusion, which prompted a CT head scan. A median hyperdense lesion that measured 22 mm in diameter was identified between the cerebellar hemispheres in the magna cistern (Figure 1). MRI, obtained using a 1.5 T superconducting magnet with contrast agent injection, showed a mass in the posterior cranial fossa that arose from the cerebellar falx and appeared slightly isointense in relation to the gray matter on
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CAVERNOUS ANGIOMA OF THE CEREBELLAR FALX
Figure 1. Preoperative scan without contrast enhancement. Axial CT image shows a median hyperdense lesion between the cerebellar hemispheres in the magna cistern that measured 22 mm in diameter.
T1-weighted imaging and markedly hyperintense on T2-weighted imaging (Figure 2). After administration of contrast medium, the mass enhanced homogeneously, and no calcification or signs of bleeding were observed. A dural tail was not identified. When the patient was referred to us, he was in good neurologic status. Surgical removal of the lesion was performed using microsurgery via a median suboccipital approach. After opening the dura, the encapsulated, red-colored tumor was exposed; the base of the implant was coagulated; and the lesion was removed en bloc, without significant intraoperative bleeding. The postoperative course was uneventful. No adjuvant therapy was required during the follow-up period. Postoperative MRI showed complete removal of the lesion (Figure 3).
Figure 2. Axial T1-weighted MR image (A) and gadolinium-enhanced axial T1-weighted MR image (B) show an extra-axial, lobulating lesion arising from the cerebellar falx with heterogeneous enhancement after gadolinium. Coronal T2-weighted MR image (C) image shows an inhomogeneous hyperintense signal.
HISTOLOGIC EXAMINATION Histologic examination showed a cavernous angioma, composed of compact, closely apposed vessels that varied considerably in caliber. The vessels were free of smooth muscle and elastic lamellae (Figure 4). This lesion is usually characterized by multiple irregular vascular channels lined by a flattened endothelium with a single cell layer. Vascular channels are separated by poor fibroconnective tissue stroma and may contain fluid blood. Ruptures or vascular thromboses may occur.
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DISCUSSION Extra-axial cavernous angiomas are uncommon and usually arise in the middle cranial fossa and cavernous sinus region (4, 37), although they have been described involving the optic chiasm and sella turcica (13, 30, 37). Other locations described in the literature are the tentorium, the convexity (14), the anterior cranial fossa (14), Meckel cave (8), the cerebellopontine angle (16), the internal auditory canal (2), and the sella turcica (5, 6). Regarding lesions of the cav-
ernous sinus, Linskey and Eskhar (21) hypothesized that cavernous angiomas originate within the dural sinuses and only secondarily extend into the middle fossa. Although cavernous angiomas have been reported arising from other dural sinuses such as the petrosal sinus and the torcular (23), this relationship is not observed in all cases. A literature review of the last 20 years of the PubMed and Cochrane Databases gave no result for cavernous angioma of the cerebellar falx. Extra-axial cavernous angiomas occur predominantly in middle-aged women (6, 27), and a possible role of hormones has been suggested because symptoms may appear or worsen during pregnancy or after hormone therapy (12, 16, 26). Rosenblum et al. (29) reported a case of cavernous angioma in a patient with Turner syndrome receiving exogenous estrogens. Presenting symptoms are usually related to the size and effects on adjacent structures, and hemorrhage is rare (37); however, Suzuki et al. (35) described a case of nontraumatic acute subdural hematoma caused by hemorrhage from a cavernous angioma located on the convexity of the dura mater. These lesions differ from hemangiomas of infancy, which are benign vascular tumors that always regress (3). Extra-axial cavernous lesions differ from intraparenchymal malformations in terms of their vascularity and imaging characteristics. They tend to present more homogeneous contrast enhancement, are highly vascular, and have a propensity to bleed at surgery (4, 27, 37). Preoperatively, they may be confused with meningiomas on the basis of their radiologic characteristics. On noncontrast CT scan, dural cavernous angiomas are reported as isodense (20, 25) or hyperdense (21, 24, 26) masses. Usually after contrast agent administration (on CT and MRI), the lesions enhance homogeneously (5, 10, 29, 32, 33). Signal intensity is usually inhomogeneous and mixed on T1weighted and T2-weighted imaging with a hypointense rim of hemosiderin on T2weighted imaging. The neuroradiologic findings, speckled nature of the lesions, and mixed intensity are the result of vascular lumens, thromboses, and calcifications within the malformation. Intra-axial cavernous angiomas usually have a multifocal hyperintense center surrounded by a hypointense rim caused by
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.07.015
PEER-REVIEW REPORTS ANGELINA GRAZIELLA MELONE ET AL.
Figure 3. Postoperative axial T1-weighted MR gadolinium-enhanced image shows total removal of the lesion.
the blood contents at different stages of evolution (13, 27, 34). The characteristic peripheral low signal rim is usually absent in
CAVERNOUS ANGIOMA OF THE CEREBELLAR FALX
extra-axial malformations; blood flow is maintained, there is no evidence of previous hemorrhage, hemosiderin is absent, and there are few calcium deposits. It is possible that hemoglobin breakdown products do not accumulate around the lesion as occurs in the brain parenchyma where macrophages containing hemosiderin circumscribe the lesion. These lesions have been reported as a soft mass often with a pseudocapsule formed by the dura mater, mimicking meningiomas. In our case, the dural tail sign and calcification were absent. As shown by Guermazi et al. (11), these two signs are rarely seen, but when they are present, differentiating cavernous angioma from meningioma is difficult. Meningiomas are usually isointense or hypointense on T1-weighted images and isointense or mildly hyperintense on T2-weighted images with intense contrast enhancement (2).Cavernous angiomas of the optic nerve, the optic chiasm,
Figure 4. Gross section (A) shows encapsulated, bleeding, red-colored lesion. Photomicrograph of histopathologic specimen (hematoxylin-eosin, 200⫻) (B) shows cavernous angioma, composed of compact, closely apposed vessels that vary considerably in caliber. The vessels are free both smooth muscle and elastic lamellae.
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and the optic tracts exhibit clinical and radiologic findings analogous to findings of intracerebral cavernoma. Angiography is also useful for diagnosing extra-axial cavernomas because it reveals the flecked lesion stain at middle arterial to late venous phases owing to slow blood flow, delayed stain, or an avascular mass. In 80% of cavernous sinus lesions, angiography is positive; other authors describe the possibility of an extra-axial malformation appearing as an avascular mass with displacement of the adjacent vessels (16, 24). In contrast to meningiomas, the sunburst of vessels radiating outward from the central vascular pedicle, a typical finding in meningiomas, has not been observed in cavernous angioma (3, 17, 28). Intracerebral lesions are angiographically occult; in our case, angiography was not performed. The role of thallium 201 single photon emission computed tomography was studied in the diagnosis of cavernous angioma. Seo et al. (31) stressed that cavernous sinus hemangioma on thallium 201 single photon emission computed tomography exhibits a low uptake within the lesion, in contrast to meningiomas or malignant tumors, which exhibit a high uptake owing to increased tumor viability or tumor blood flow (much higher within meningiomas compared with malignant tumors). Regarding the surgical treatment of these malformations, bleeding represents a major problem at the cavernous sinus level (42%) (21). In other extra-axial cavernous angioma locations, little intraoperative blood loss was reported, however; this is similar to our experience, in which total removal was achieved without particular difficulty. Macroscopically, a cavernous angioma appears as a soft mass, often with a pseudocapsule that is formed by the dura mater (16, 20, 21), as in our case. No adjuvant therapy was required during the follow-up period. Histopathologically, intracerebral and extra-axial cavernous angiomas are identical lesions (3). The treatment of choice is total surgical removal. In cases of partial removal, as in cavernous sinus angioma, it is possible treat the patient with radiosurgery, obtaining a marked shrinkage of the tumor. Intracranial extradural tumors are more radiosensitive than intracerebral cavernous angiomas (31).
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REFERENCES 1. Ahmadi J, Miller CA, Segall HD, Park SH, Zee CS, Becker RL: CT patterns in histopathologically complex cavernous hemangiomas. ANJR Am J Neuroradiol 6:389-93, 1985. 2. Aoki S, Sasaki Y, Machida T, Tanioka H: Contrastenhanced MR images in patients with meningioma: importance of enhancement of the dura adjacent to the tumor. ANJR Am J Neuroradiol 11:935-8, 1990. 3. Biondi A, Clemenceau S, Dormont D, Deladoeuille M, Ricciardi GK, Mokhtari K, Sichez JP, Marsault C: Intracranial extra-axial cavernous (hem)angiomas: tumors or vascular malformations? Report of five cases and review of the literature. J Neuroradiol 29: 91-104, 2002. 4. Bristot R, Santoro A, Fantozzi L, Delfini R: Cavernoma of the cavernous sinus: case report. Surg Neurol 48:160-3, 1997. 5. Buonaguidi R, Canapicci R, Mimassi N, Ferdeghini M: Intrasellar cavernous emangioma. Neurosurgery 14:732-4, 1984. 6. Eisenberg MB, Al Mefty O, DeMonte F, Burson GT: Benign nonmeningeal tumors of the cavernous sinus. Neurosurgery 44:949-54, 1999. 7. Escott EJ, Rubinstein D, Cajade-Law AG, Sze CI: Suprasellar cavernous malformation presenting with extensive subarachnoid hemorrhage. Neuroradiology 43:313-6, 2001. 8. Fehlings MG, Tucker WS: Cavernous hemangioma of Meckel’s cave. Case report. J Neurosurg 68: 645-7, 1988. 9. Ferrante L, Acqui M, Trillo G, Antonio M, Narducci B, Celli P: Cavernous angioma of the VIII th cranial nerve. A case report. Neurosurg Rev 21:270-6, 1998. 10. Gliemroth J, Missler U, Sepehrnia A: Cavernous angiomas as a rare neuroradiologic finding in the cavernous sinus. J Clin Neurosci 7:554-7, 2000. 11. Guermazi A, Lafitte F, Miaux Y, Adem C, Bonneville JF, Chiras J: The dural tail sign— beyond meningioma. Clin Radiol 60:171-88, 2005. 12. Heckl S, Aschoff A, Kunze S: Cavernomas of the skull: review of the literature 1975-2000. Neurosurg Rev 25:56-62, 2002. 13. Hwang JF, Yau CW, Huang JK, Tsai CY: Apoplectic optochiasmal syndrome due to intrinsic cavernous hemangioma. Case report. J Clin Neuroophthalmol 13:232-6, 1993.
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14. Hyodo A, Yanaka K, Higuchi O, Tomono Y, Nose T: Giant interdural cavernous hemangioma at the convexity. Case illustration. J Neurosurg 92:503, 2000. 15. Iplikcioglu AC, Benli K, Bertan V, Ruacan S: Cystic cavernous hemangioma of the cerebello-pontine angle: case report. Neurosurgery 19:641-2, 1986. 16. Isla A, Roda JM, Alvarez F, Munoz J, Garcia E, Blazquez MG: Intracranial cavernous angioma in the dura. Neurosurgery 25:657-9, 1989. 17. Kaga A, Isono M, Mori T, Kusakabe T, Okada H, Hori S: Cavernous angioma of falx cerebri: case report. No Shinkei Geka 19:1079-83, 1991. 18. Katayama Y, Tsubokawa T, Miyazaki S, Yoshida K, Himi K: Magnetic resonance imaging of cavernous sinus cavernous hemangiomas. Neuroradiology 33: 118-22, 1991. 19. Kim JS, Yang SH, Kim MK, Hong YK: Cavernous angioma in the falx cerebri: a case report. J Korean Med Sci 21:950-3, 2006. 20. Kudo T, Ueki S, Kobayashi H, Torigoe H, Tadokoro M: Experience with the ultrasonic surgical aspirator in a cavernous hemangioma of the cavernous sinus. Neurosurgery 24:628-31, 1989. 21. Linskey ME, Eskhar LN: Cavernous sinus hemangiomas: a series, a review, and an hypothesis. Neurosurgery 30:101-8, 1992. 22. Matias-Guiu X, Alejo M, Sole T, Ferrer I, Noboa R, Bartumeus F: Cavernous angiomas of the cranial nerves. Report of two cases. J Neurosurg 73:620-2, 1990. 23. Meyer FB, Lombardi D, Scheithauer B, Nicholas DA: Extra-axial cavernous hemangiomas involving the dural sinuses. J Neurosurg 73:187-92, 1990. 24. Momoshima S, Shiga H, Yuasa Y, Higuchi N, Kawase T, Toya S: MR findings in extra-cerebral cavernous angiomas of the middle cranial fossa: report of two cases and review of the literature. AJNR Am J Neuroradiol 12:756-60, 1991. 25. Moore T, Ganti SR, Mawad ME, Hilal SK: CT and angiography of primary extradural juxtasellar tumors. AJR Am J Roentgenol 145:491-6, 1985. 26. Namba S: Extra-cerebral cavernous hemangioma of the middle cranial fossa. Surg Neurol 19:379-88, 1983. 27. Rigamonti D, Pappas CTE, Spetzler RF, Johnson PC: Extracerebral cavernous angiomas of the middle fossa. Neurosurgery 27:306-10, 1990.
28. Robinson JR Jr, Awad IA, Masaryk TJ, Estes ML: Pathological heterogeneity of angiographically occult vascular malformations of the brain. Neurosurgery 33:547-55, 1993. 29. Rosenblum B, Rothman AS, Lanzieri C, Song S: A cavernous sinus cavernous hemangioma. Case report. J Neurosurg 65:716-8, 1986. 30. Sansone ME, Liwnicz BH, Mandybur TI: Giant pituitary cavernous hemangioma. Case report. J Neurosurg 53:124-6, 1980. 31. Seo Y, Fukuoka S, Sasaki T, Takanashi M, Hojo A, Nakamura H: Cavernous sinus hemangioma treated with gamma knife radiosurgery: usefulness of SPECT for diagnosis— case report. Neurol Med Chir 40:575-78, 2000. 32. Shen WC, Chenn CA, Hsue CT, Lin TY: Dural cavernous angioma mimicking a meningioma and causing facial pain. J Neuroimaging 10:183-5, 2000. 33. Shibata S, Mori K: Effect of radiation therapy on extra-cerebral cavernous hemangioma in the middle fossa. Report of three cases. J Neurosurg 67:91922, 1987. 34. Stato M, Nakano M, Susanuma M, Asari J, Watanabe K, Hanai K: MR image of multiple intracranial cavernous angioma: the usefulness of gradient-echo MR image. No To Shinkei 55:172-3, 2003. 35. Suzuki K, Kamezaki T, Tsuboi K, Kobayashi E: Dural cavernous angioma causing acute subdural hemorrhage— case report. Neurol Med Chir (Tokyo) 36: 580-2, 1996. 36. Voelker JL, Stewart DH, Schochet SS Jr: Giant intracranial and extra-cranial cavernous malformation. Case report. J Neurosurg 89:465-9, 1998. 37. Zabramski JM, Awasthi D: Extra-axial cavernous malformations. In: Awald IA, Barrow DL, eds: Cavernous Malformations. Park Ridge, IL: American Association of Neurological Surgeons; 1993: 133-44.
received 16 March 2010; accepted 08 July 2010 Citation: World Neurosurg. (2010) 74, 4/5:501-504. DOI: 10.1016/j.wneu.2010.07.015 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2010 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.07.015
Intracranial Extra-axial Cavernous Angioma of the Cerebellar Falx Angelina Graziella Melone, Catia P. Delfinis, Emiliano Passacantilli, Jacopo Lenzi, Antonio Santoro
䡲 INTRODUCTION: Intracranial cavernous hemangiomas are benign vascular malformations that can be divided into intra-axial and extra-axial types. Extra-axial cavernous angiomas (or hemangiomas) are rare lesions; intracranially, they arise in relation to the dura mater or at a spinal level mimicking meningiomas. They are very rarely reported in the posterior cranial fossa. 䡲 CASE REPORT: The authors report a case of a cavernous angioma that occurred in the cerebellar falx of a 58-year-old man. The lesion was discovered during cranial computed tomography (CT) and magnetic resonance imaging (MRI) examinations. The patient underwent surgery with en-bloc removal of the tumor. No significant intraoperative bleeding or complications occurred during the postoperative course. 䡲 CONCLUSION: Intra-axial and extra-axial cavernous angiomas are histopathologically identical lesions, but by the radiological features, it is very difficult to distinguish the extra-axial cavernous angiomas from meningiomas, especially when dural tail sign and calcification are present.
INTRODUCTION Intracranial cavernous angiomas are usually intraparenchymal, extra-axial malformations and are relatively rare, accounting for only 0.4%–2% of all intracranial vascular malformations (3, 19, 37). They have very rarely been reported as the cause of subarachnoid hemorrhage, in contrast to the intra-axial type (6). In relation to their attachment to the dura, they mimic meninKey words 䡲 Cerebellar falx 䡲 Extra-axial cavernous angioma 䡲 Hemangioma 䡲 Intra-axial cavernous angioma Abbreviations and Acronyms CT: Computed tomography MRI: Magnetic resonance imaging From the Department of Neurological ScienceNeurosurgery, University “Sapienza,” Rome, Italy To whom correspondence should be addressed: Angelina Graziella Melone, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2010) 74, 4/5:501-504. DOI: 10.1016/j.wneu.2010.07.015 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2010 Elsevier Inc. All rights reserved.
giomas, although their radiologic features appear quite different from intra-axial cavernomas. On computed tomography (CT) scan, extra-axial cavernous angiomas are isodense or hyperdense masses, showing homogeneous contrast enhancement. On T2-weighted magnetic resonance imaging (MRI), intra-axial cavernous angiomas usually exhibit a multifocal hyperintense center surrounded by a hypointense rim resulting from the blood products at different stages of evolution inside; on T1-weighted imaging, they appear isointense. Differential diagnosis of meningiomas is difficult because extra-axial cavernous angiomas appear isointense or hypointense on T1-weighted images and isointense or mildly hyperintense on T2-weighted images, showing intense contrast enhancement (2); extra-axial cavernous angiomas may exhibit a dural tail sign and calcifications, two findings typical of meningiomas. Grossly, cavernous angiomas are typically multilobulated lesions dark red to blue in color that contain hemic products at various stages of evolution. Histologically, these lesions are characterized by vascular channels lined with fibroconnective tissue stroma. The histologic architecture of the
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component vessels resembles that of capillary telangiectasias, consisting of a single layer of endothelium and varying quantities of subendothelial fibrous stroma, with a distinct absence of smooth muscle and elastic fibers. Regardless of their location, cavernous malformations are identical on histology, immunohistochemistry, and electron microscopy (3). Extra-axial lesions usually arise in relation to the dura mater intracranially or at a spinal level (3). Most of these malformations are found in the middle cranial fossa at the level of the cavernous sinus (1-18) and only rarely are found in other dural locations outside the middle fossa, such as the convexity (14), the anterior cranial fossa (15), the cerebellopontine angle (16), and Meckel cave (8). A few lesions have been described in the sellar and suprasellar region (5, 7), at the level of the cranial nerves (9, 15), and in the internal auditory canal (22). Skull extension (36) and intraosseous lesions of the skull (12) have also been reported. A few cases have originated from the falx cerebri (19). An English literature review of the last 20 years of the PubMed and Cochrane Databases yielded no results for cavernous angioma of the cerebellar falx. We report the case of a 58-year-old man in whom a cavernous angioma of the cerebellar falx was found, paying particular attention to its neuroradiologic features. The lesion was successfully removed.
CASE REPORT A 58-year-old man experienced an episode of mental confusion, which prompted a CT head scan. A median hyperdense lesion that measured 22 mm in diameter was identified between the cerebellar hemispheres in the magna cistern (Figure 1). MRI, obtained using a 1.5 T superconducting magnet with contrast agent injection, showed a mass in the posterior cranial fossa that arose from the cerebellar falx and appeared slightly isointense in relation to the gray matter on
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Figure 1. Preoperative scan without contrast enhancement. Axial CT image shows a median hyperdense lesion between the cerebellar hemispheres in the magna cistern that measured 22 mm in diameter.
T1-weighted imaging and markedly hyperintense on T2-weighted imaging (Figure 2). After administration of contrast medium, the mass enhanced homogeneously, and no calcification or signs of bleeding were observed. A dural tail was not identified. When the patient was referred to us, he was in good neurologic status. Surgical removal of the lesion was performed using microsurgery via a median suboccipital approach. After opening the dura, the encapsulated, red-colored tumor was exposed; the base of the implant was coagulated; and the lesion was removed en bloc, without significant intraoperative bleeding. The postoperative course was uneventful. No adjuvant therapy was required during the follow-up period. Postoperative MRI showed complete removal of the lesion (Figure 3).
Figure 2. Axial T1-weighted MR image (A) and gadolinium-enhanced axial T1-weighted MR image (B) show an extra-axial, lobulating lesion arising from the cerebellar falx with heterogeneous enhancement after gadolinium. Coronal T2-weighted MR image (C) image shows an inhomogeneous hyperintense signal.
HISTOLOGIC EXAMINATION Histologic examination showed a cavernous angioma, composed of compact, closely apposed vessels that varied considerably in caliber. The vessels were free of smooth muscle and elastic lamellae (Figure 4). This lesion is usually characterized by multiple irregular vascular channels lined by a flattened endothelium with a single cell layer. Vascular channels are separated by poor fibroconnective tissue stroma and may contain fluid blood. Ruptures or vascular thromboses may occur.
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DISCUSSION Extra-axial cavernous angiomas are uncommon and usually arise in the middle cranial fossa and cavernous sinus region (4, 37), although they have been described involving the optic chiasm and sella turcica (13, 30, 37). Other locations described in the literature are the tentorium, the convexity (14), the anterior cranial fossa (14), Meckel cave (8), the cerebellopontine angle (16), the internal auditory canal (2), and the sella turcica (5, 6). Regarding lesions of the cav-
ernous sinus, Linskey and Eskhar (21) hypothesized that cavernous angiomas originate within the dural sinuses and only secondarily extend into the middle fossa. Although cavernous angiomas have been reported arising from other dural sinuses such as the petrosal sinus and the torcular (23), this relationship is not observed in all cases. A literature review of the last 20 years of the PubMed and Cochrane Databases gave no result for cavernous angioma of the cerebellar falx. Extra-axial cavernous angiomas occur predominantly in middle-aged women (6, 27), and a possible role of hormones has been suggested because symptoms may appear or worsen during pregnancy or after hormone therapy (12, 16, 26). Rosenblum et al. (29) reported a case of cavernous angioma in a patient with Turner syndrome receiving exogenous estrogens. Presenting symptoms are usually related to the size and effects on adjacent structures, and hemorrhage is rare (37); however, Suzuki et al. (35) described a case of nontraumatic acute subdural hematoma caused by hemorrhage from a cavernous angioma located on the convexity of the dura mater. These lesions differ from hemangiomas of infancy, which are benign vascular tumors that always regress (3). Extra-axial cavernous lesions differ from intraparenchymal malformations in terms of their vascularity and imaging characteristics. They tend to present more homogeneous contrast enhancement, are highly vascular, and have a propensity to bleed at surgery (4, 27, 37). Preoperatively, they may be confused with meningiomas on the basis of their radiologic characteristics. On noncontrast CT scan, dural cavernous angiomas are reported as isodense (20, 25) or hyperdense (21, 24, 26) masses. Usually after contrast agent administration (on CT and MRI), the lesions enhance homogeneously (5, 10, 29, 32, 33). Signal intensity is usually inhomogeneous and mixed on T1weighted and T2-weighted imaging with a hypointense rim of hemosiderin on T2weighted imaging. The neuroradiologic findings, speckled nature of the lesions, and mixed intensity are the result of vascular lumens, thromboses, and calcifications within the malformation. Intra-axial cavernous angiomas usually have a multifocal hyperintense center surrounded by a hypointense rim caused by
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.07.015
PEER-REVIEW REPORTS ANGELINA GRAZIELLA MELONE ET AL.
Figure 3. Postoperative axial T1-weighted MR gadolinium-enhanced image shows total removal of the lesion.
the blood contents at different stages of evolution (13, 27, 34). The characteristic peripheral low signal rim is usually absent in
CAVERNOUS ANGIOMA OF THE CEREBELLAR FALX
extra-axial malformations; blood flow is maintained, there is no evidence of previous hemorrhage, hemosiderin is absent, and there are few calcium deposits. It is possible that hemoglobin breakdown products do not accumulate around the lesion as occurs in the brain parenchyma where macrophages containing hemosiderin circumscribe the lesion. These lesions have been reported as a soft mass often with a pseudocapsule formed by the dura mater, mimicking meningiomas. In our case, the dural tail sign and calcification were absent. As shown by Guermazi et al. (11), these two signs are rarely seen, but when they are present, differentiating cavernous angioma from meningioma is difficult. Meningiomas are usually isointense or hypointense on T1-weighted images and isointense or mildly hyperintense on T2-weighted images with intense contrast enhancement (2).Cavernous angiomas of the optic nerve, the optic chiasm,
Figure 4. Gross section (A) shows encapsulated, bleeding, red-colored lesion. Photomicrograph of histopathologic specimen (hematoxylin-eosin, 200⫻) (B) shows cavernous angioma, composed of compact, closely apposed vessels that vary considerably in caliber. The vessels are free both smooth muscle and elastic lamellae.
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and the optic tracts exhibit clinical and radiologic findings analogous to findings of intracerebral cavernoma. Angiography is also useful for diagnosing extra-axial cavernomas because it reveals the flecked lesion stain at middle arterial to late venous phases owing to slow blood flow, delayed stain, or an avascular mass. In 80% of cavernous sinus lesions, angiography is positive; other authors describe the possibility of an extra-axial malformation appearing as an avascular mass with displacement of the adjacent vessels (16, 24). In contrast to meningiomas, the sunburst of vessels radiating outward from the central vascular pedicle, a typical finding in meningiomas, has not been observed in cavernous angioma (3, 17, 28). Intracerebral lesions are angiographically occult; in our case, angiography was not performed. The role of thallium 201 single photon emission computed tomography was studied in the diagnosis of cavernous angioma. Seo et al. (31) stressed that cavernous sinus hemangioma on thallium 201 single photon emission computed tomography exhibits a low uptake within the lesion, in contrast to meningiomas or malignant tumors, which exhibit a high uptake owing to increased tumor viability or tumor blood flow (much higher within meningiomas compared with malignant tumors). Regarding the surgical treatment of these malformations, bleeding represents a major problem at the cavernous sinus level (42%) (21). In other extra-axial cavernous angioma locations, little intraoperative blood loss was reported, however; this is similar to our experience, in which total removal was achieved without particular difficulty. Macroscopically, a cavernous angioma appears as a soft mass, often with a pseudocapsule that is formed by the dura mater (16, 20, 21), as in our case. No adjuvant therapy was required during the follow-up period. Histopathologically, intracerebral and extra-axial cavernous angiomas are identical lesions (3). The treatment of choice is total surgical removal. In cases of partial removal, as in cavernous sinus angioma, it is possible treat the patient with radiosurgery, obtaining a marked shrinkage of the tumor. Intracranial extradural tumors are more radiosensitive than intracerebral cavernous angiomas (31).
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received 16 March 2010; accepted 08 July 2010 Citation: World Neurosurg. (2010) 74, 4/5:501-504. DOI: 10.1016/j.wneu.2010.07.015 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2010 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.07.015