pISSN 1598-298X
J Vet Clin 31(2) :152-155 (2014)
152
Lumbar Angiomatous Meningioma in a Dog
Jung-min Sohn, Bo-eun Kim, Sun-young Jung, Seo-yeoun Ji, Dae-young Yoon, Oh-kyeong Kweon, Dae-yong Kim, Min-cheol Choi and Junghee Yoon1
College of Veterinary Medicine and the Research Institute for Veterinary Science, Seoul National University, Seoul 151-742, Korea (Accepted: April 10, 2014)
Abstract : An 11-year-old castrated Schnauzer presented with paraplegia for the last two weeks, initially developed pelvic limb ataxia 6 months ago and left pelvic limb paresis 3 months ago. On neurological examination, paraplegia and postural reaction deficits were noted in the pelvic limbs with no deep pain sensation, and the dog showed exaggerated spinal reflexes and involuntary urination. Magnetic resonance (MR) images of thoracolumbar spinal cord were obtained with a 0.3 Tesla magnet. A mass with a broad base to the dorsal and left dural margins was identified at the level of L2, causing marked spinal cord compression. The mass showed isointensity to the spinal cord on T1- weighted (T1W) precontrast images, hyperintensity on T2-weighted images, marked homogeneous contrast enhancement with well-defined margins and the “dural tail” sign on T1W postcontrast images. An intradural-extramedullay tumor was considered, most likely, meningioma was highly suggestive. Left-sided hemilaminectomy and dorsal laminectomy were performed. An intradural mass partially adherent to dura mater was compressing the spinal cord, and the mass was completely removed with the attached dura mater. A histopathologic diagnosis of angiomatous subtype meningioma was made.
Key words : spinal cord, angiomatous meningioma, MR imaging, hemilaminectomy, prognosis.
Introduction
Meningioma is the most common primary spinal cord neo- plasm in dogs (3,15,18). Spinal meningioma represents 15%
of all central nervous system (CNS) meningioma and has a predilection for the cervical spinal cord (15). Spinal meningi- omas are typically located in the intradural-extramedullary space, grow slowly, and cause a chronic, progressive myelop- athy with mild to moderate spinal pain, weakness, or sensory or motor deficits from ataxia to nonambulatory states and uri- nary incontinence (1,11,15,21). Advanced imaging such as computed tomography (CT) with myelogram or magnetic resonance (MR) imaging and cerebrospinal fluid (CSF) anal- ysis may result in a tentative diagnosis and aid in surgical planning, however, a definitive diagnosis is made by histopa- thology (1,15,21). Therapy is aimed at alleviating spinal cord compression by either medically or surgically (1). Prognosis is guarded to good depending on resectability, histologic type, location, and severity of neurologic signs (1,11,15,17,18). The purpose of this report is to describe a case of angiomatous meningioma in the lumbar spinal cord in a dog and provide MR imaging features, intraoperative findings, and prognosis following surgical treatment.
Case
An 11-year-old castrated Schnauzer presented with a 2-week history of paraplegia. The dog initially developed pelvic limb ataxia 6 months before, and it worsened to left pelvic limb paresis 3 months later. On neurological examination, paraple- gia and postural reaction deficits were noted in the pelvic limbs with no deep pain sensation, and the dog showed exag- gerated spinal reflexes and involuntary urination. The lesion was localized on the thoracolumbar spine. On hematology, serum biochemistry, and urinalysis, no abnormalities were detected except for mildly increased alkaline phosphatase activity at 189 U/l (reference interval: 8-100 U/l).
Thoracic, abdominal, and thoracolumbar spinal radiogra- phy and abdominal ultrasound were performed, and rela- tively narrowed intervertebral disc space between L1 and L2 was identified (Fig 1). Otherwise, in regard to clinical signs of neurologic dysfunction, no remarkable findings were detected on radiography and ultrasound.
MR images of thoracolumbar spinal cord were obtained with a 0.3 T magnet under general anesthesia in the dog. A half-oval shaped mass causing marked spinal cord compres- sion was present in the region of L2, from middle part of L2 to the intervertebral space between L2 and L3, and had a broad base to the dorsal and left dural margins. The mass was isointense to the spinal cord on T1-weighted (T1W) pre- contrast images and hyperintense on T2-weighted (T2W) images (Fig 2). On T1W postcontrast images, marked homo-
1Corresponding author.
E-mail: [email protected]
Lumbar Angiomatous Meningioma in a Dog 153
geneous contrast enhancement with well-defined margins and the “dural tail” sign were identified (Fig 3). Fluid-attenuated inversion recovery (FLAIR) images showed hyperintensity of the spinal cord adjacent to the mass, consistent with parenchy- mal edema. Based on the MR imaging features, an intradural- extramedullary tumor was considered, most likely, meningi- oma was highly suggestive. Additionally, generalized disc degeneration and intervertebral disc diseases with mild spi- nal cord compression at T13-L1 and L1-L2 were identified.
Left-sided hemilaminectomy and dorsal laminectomy were performed at L1-L3, and the spinal cord was exposed. Upon exposure an intradural lesion was evident, a soft tissue mass compressing the parenchyma and regional parenchymal edema in the region of L2 was identified, which was consis- tent with the extent of lesion identified on MR images. A durotomy was performed and the mass was carefully dis- sected from the spinal cord, as the mass was partially
adhered to dura mater, the attached dura mater was removed with the mass. As the mass was removed, partial expansion of the regional spinal cord was identified. A histopathologic diagnosis of angiomatous subtype meningioma was made.
The mass was encapsulated by connective tissues and no evi- dence of invasion to surrounding tissues was identified.
The dog showed progressive improvement of clinical signs: deep and superficial pain sensation returned 4 and 14 days after surgery, respectively, and the dog showed para- paresis with 11 of Olby score (weight-bearing protraction of pelvic limb 100% of the time with reduced strength, mis- takes < 50% of the time) (13) within a month after surgery and no deterioration until the time of writing (9 months after surgery).
Discussion
Primary spinal cord neoplasm occurs rarely in dogs (21).
Although meningioma is the most common primary neo- plasm in CNS in dogs (1), spinal cord meningioma occurs much less frequently than intracranial one: 82% of all menin- giomas were located intracranially and 15% intraspinally (1,3). Spinal cord meningiomas in dogs have been reported sporadically (2-3,6,10-12,16-17,21), however, mostly they were cases of meningiomas occurring in the cervical spinal cord region (2,11,15-17). In one study, the distribution of spi- nal meningiomas in dogs was 27% in the cervical, 47% in the thoracic, and 27% in the lumbar spinal cord region (1), and in another study, 68% in the cervical, 4% in the tho- racic, and 23% in the lumbar spinal cord region (15).
Histologically, canine meningiomas are classified by the World Health Organization (WHO) classification system for Fig 1. Survey spinal radiographs showing narrowing of the inter-
vertebral disc space at L1-L2 on lateral (A) and ventrodorsal (B) view.
Fig 2. Sagittal and transverse T1W precontrast (A, B) and T2W (C, D) MR images. Note the mass with the broad base to the dorsal and left dural margin at the level of L2 showing isoin- tensity on T1W and hyperintensity on T2W images.
Fig 3. Dorsal (A), sagittal (B), and transverse (C) T1W post- contrast MR images. Note the homogenously contrast-enhanc- ing mass with the “dural tail” sign.
154 Jung-min Sohn et al.
canine meningiomas as meningotheliomatous, fibrous (fibro- blastic), transitional (mixed), psammomatous, angiomatous (angioblastic), papillary, granular cell, myxoid, or anaplastic (malignant) (7), however, this classification system doesn’t include all of the histologic subtypes. The WHO classifica- tion system for human meningiomas includes more histologic subtypes and provides tumor grade indicative of malignancy potential of a tumor: meningothelial, fibrous (fibroblastic), transitional (mixed), psammomatous, angiomatous, microcys- tic, secretory, lymphoplasmacyte rich, and metaplastic sub- types as grade 1, atypical, clear cell, and chordoid subtypes as grade 2, and papillary, rhabdoid, and anaplastic (malig- nant) subtypes as grade 3 (8). Histologic subtypes in canine spinal cord meningiomas have been described in several reports (2,10-12,15,21), meningothelial and transitional sub- types were the two most common meningeal variants (2,10- 12) and, to the authors’ knowledge, there was no report of angiomatous subtype in spinal cord meningioma in dogs.
Although definitive diagnosis is made by histopathology, an antemortem tentative diagnosis is made by history and clinical signs, exclusion of another primary tumor or malig- nancy elsewhere in the body, and advanced imaging such as MR imaging (1).
The MR imaging features of spinal cord meningiomas in dogs are marked contrast enhancement, which is usually homogenous but often heterogeneous (1,6,11,15,18). Signal intensity is variable, however, the most common changes seen with MR imaging are iso- or hypointensity on T1W images, hyperintensity on T2W images, homogenous con- trast enhancement, and the presence of edema (1,6,11,15,18).
In this case study, isointensity on T1W images, hyperinten- sity on T2W images, marked homogeneous contrast enhance- ment, and parenchymal edema on FLAIR images were identified, which was consistent with features reported previ- ously.
No significant correlations were found between MR imag- ing features and tumor subtype or grade in dogs (15,18). In human, some studies found no significant associations, whereas others found that T2W signal intensity tended to be correlated with the histologic subtype (4,5,9,19). Tumors with hyperintensity on both T1W and T2W images, extensive edema, central necrosis, and irregular borders have been re- ported to have tendency to show more aggressive behavior (5).
The primary purpose of treatment is to reduce spinal cord compression, which may be achieved medically or surgi- cally, through either complete resection or cytoreduction of the tumor (1). Prognosis is guarded to good depending on resectability, location, and histologic type of tumor as well as severity of neurologic signs (1,11,15,17-18).
Prognosis may be more favorable where complete resec- tion of the tumor is achieved, however, spinal cord meningio- mas in dogs tend to be infiltrative (1,15), whereas intracranial meningiomas in dogs or cats or spinal meningiomas in cats tend to less adherent to the surrounding tissues (1,14), and complete removal may be difficult. In addition, ventrally
located tumors or tumors at C1-C3 are often associated with poorer prognosis (15). Even after complete surgical removal of tumor and adjuvant radiation therapy, canine meningio- mas tend to recur (1,11,15,20).
In this case study, tumor was found relatively well circum- scribed on MR images, though partial adhesion to dura mater was identified on surgery, located dorsally at lumbar region, and complete removal with the attached dura mater was pos- sible. Histologically, tumor was diagnosed as angiomatous subtype, a benign form of meningioma. Tumor was encapsu- lated by connective tissues and no infiltrative features were found. Hence, the dog was expected to show favorable prog- nosis, and indeed have been showed progressive improve- ment of neurologic signs.
Conclusion
MR imaging features in this case study were similar in those previously reported, and aided in determining resect- ability and eventually surgical planning of the tumor. The tumor was completely removed, diagnosed histologically as a benign angiomatous meningioma, and the dog showed favor- able prognosis.
References
1. Adamo PF, Forrest L, Dubielzig R. Canine and feline me- ningiomas: diagnosis, treatment, and prognosis. Compend Contin Educ Pract Vet 2004; 26: 951-965.
2. Barnhart KF, Wojcieszyn J, Storts RW. Immunohistochemical staining patterns of canine meningiomas and correlation with published immunophenotypes. Vet Pathol 2002; 39: 311-321.
3. De Bosschere H, Vermeersch K, Tshamala M, Van De Velde B, Hoybergs Y, Van Ham L, Ducatelle R. Lumbar atypical meningioma in a dog. Vlaams Diergeneeskundig Tijdschrift 2003; 72: 295-298.
4. Chen TC, Zee CS, Miller CA, Weiss MH, Tang G, Chin L, Levy ML, Apuzzo ML. Magnetic resonance imaging and pathological correlates of meningiomas. Neurosurgery 1992;
31: 1015-1021; discussion 1021-1022.
5. Engelhard HH. Progress in the diagnosis and treatment of patients with meningiomas. Part 1: diagnostic imaging, pre- operative embolization. Surg Neurol 2001; 55: 88-101.
6. Kippenes H, Gavin PR, Bagley RS, Silver GM, Tucker RL, Sande RD. Magnetic resonance imaging features of tumors of the spine and spinal cord in dogs. Vet Radiol Ultrasound 1999; 40: 627-633.
7. Koestner A, Bilzer T, Fatzer R, Schulman FY, Summers BA, Van Winkle TJ. World Health Organization: Histological Classification of Tumors of the Nervous System of Domestic Animals, 2nd ed. Washington, DC: Armed Forces Institute of Pathology. 1999: 27-29.
8. Louis DN, Ohgaki H, Wiestler OD, Cavenee WK, Burger PC, Jouvet A, Scheithauer BW, Kleihues P. The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol 2007; 114: 97-109.
9. Maiuri F, Iaconetta G, De Divitiis O, Cirillo S, Di Salle F, De Caro ML. Intracranial meningiomas: correlations between
Lumbar Angiomatous Meningioma in a Dog 155
MR imaging and histology. Eur J Radiol 1999; 31: 69-75.
10. Mandara MT, Ricci G, Rinaldi L, Sarli G, Vitellozzi G. Im- munohistochemical identification and image analysis quanti- fication of oestrogen and progesterone receptors in canine and feline meningioma. J Comp Pathol 2002; 127: 214-218.
11. McDonnell JJ, Tidwell AS, Faissler D, Keating J. Magnetic resonance imaging features of cervical spinal cord menin- giomas. Vet Radiol Ultrasound 2005; 46: 368-374.
12. Montoliu P, Anor S, Vidal E, Pumarola M. Histological and immunohistochemical study of 30 cases of canine menin- gioma. J Comp Pathol 2006; 135: 200-207.
13. Olby NJ, De Risio L, Munana KR, Wosar MA, Skeen TM, Sharp NJ, Keene BW. Development of a functional scoring system in dogs with acute spinal cord injuries. Am J Vet Res 2001; 62: 1624-1628.
14. Patnaik AK, Kay WJ, Hurvitz AI. Intracranial meningioma: a comparative pathologic study of 28 dogs. Vet Pathol 1986;
23: 369-373.
15. Petersen SA, Sturges BK, Dickinson PJ, Pollard RE, Kass PH, Kent M, Vernau KM, LeCouteur RA, Higgins RJ.
Canine intraspinal meningiomas: imaging features, histo- pathologic classification, and long-term outcome in 34 dogs.
J Vet Intern Med 2008; 22: 946-953.
16. Raskin RE. An atypical spinal meningioma in a dog. Vet Pathol 1984; 21: 538-540.
17. Siegel S, Kornegay JN, Thrall DE. Postoperative irradiation of spinal cord tumors in 9 dogs. Vet Radiol Ultrasound 1996; 37: 150-153.
18. Sturges BK, Dickinson PJ, Bollen AW, Koblik PD, Kass PH, Kortz GD, Vernau KM, Knipe MF, LeCouteur RA, Higgins RJ. Magnetic resonance imaging and histological classification of intracranial meningiomas in 112 dogs. J Vet Intern Med 2008; 22: 586-595.
19. Suzuki Y, Sugimoto T, Shibuya M, Sugita K, Patel SJ.
Meningiomas: correlation between MRI characteristics and operative findings including consistency. Acta Neurochir (Wien) 1994; 129: 39-46.
20. Theon AP, Lecouteur RA, Carr EA, Griffey SM. Influence of tumor cell proliferation and sex-hormone receptors on effectiveness of radiation therapy for dogs with incompletely resected meningiomas. J Am Vet Med Assoc 2000; 216:
701-707.
21. Wall M, Platt S, Selcer B, Brockus C, Howerth E. Multifocal spinal papillary meningioma in a dog. Vet Radiol Ultrasound 2005; 46: 309-312.
개에서 발생한 요추 혈관종성수막종 증례
손정민·김보은·정선영·지서연·윤대영·권오경·김대용·최민철·윤정희1
서울대학교 수의과대학
요 약 : 11년령의 중성화된 수컷 Schnauzer 가 후지마비 증상으로 내원하였다. 6개월 전부터 후지의 운동실조를 보이 다가 3개월 전부터는 좌측 후지의 불완전마비를 보였으며, 2주 전부터는 양측 후지의 완전마비 증상을 나타내었다. 신 경계 검사에서 양측 후지의 완전마비와 자세반사 및 심부통 소실이 확인되었으며, 척수반사는 항진되어 있었고 자발 배뇨는 불가능한 상태였다. 흉요추 부위의 MR (0.3 Tesla) 영상 검사가 실시되었다. 척수를 심하게 압박하는 하나의 종괴가 요추 2번 수준에서 확인되었으며, 종괴는 좌측 및 등쪽으로 경질막과 넓게 접하고 있었다. 종괴는 T1 강조 영 상에서 척수와 비슷한 신호 강도를 보였으며, T2 강조 영상에서는 고신호를 보였다. 조영 후 T1 강조 영상에서는 고 도의 균일한 조영 증강을 보였으며, 경계는 명확하고 “dural tail sign” 을 동반하고 있었다. 이러한 영상학적 특징으로 부터 경질막내 척수외 종양이 고려되었으며, 그 중에서도 수막종이 가장 우선적으로 고려되었다. 좌측 편측후궁절제술 및 등쪽 후궁절제술이 실시되었다. 부분적으로 경질막과 유착되어 있는 하나의 경질막내 종괴가 척수를 압박하고 있 는 것이 확인되었고, 종괴는 유착된 경질막 부분과 함께 완전히 제거되었다. 조직병리학적 검사를 통해 혈관종성수막 종으로 진단되었다.
주요어 : 척수, 혈관종성수막종, MR 영상, 편측후궁절제술, 예후
