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| Year : 2014 | Volume
: 57
| Issue : 2 | Page : 357-358 |
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| Mediastinal mass: Arteriovenous malformation |
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Pooja Singhal1, Adriana Luk2, Elsie Nyugen3, Jagdish Butany1
1 Department of Pathology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
2 Departments of Medicine, Division of Cardiology, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
3 Department of Medical Imaging, Cardiothoracic Division, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
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| Date of Web Publication | 19-Jun-2014 |
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How to cite this article:
Singhal P, Luk A, Nyugen E, Butany J. Mediastinal mass: Arteriovenous malformation. Indian J Pathol Microbiol 2014;57:357-8 |
Sir,
Arteriovenous malformations (AVMs) are developmental anomalies characterized by an abnormal connection between arteries and veins, bypassing the capillaries. AVM can occur at any location; however, mediastinal AVM are rare and generally associated with a history of trauma. [1] Congenital mediastinal AVM are even rarer and may be associated with other hereditary disorders such as hereditary hemorrhagic telangiectasia (Osler-Weber Rendu). [1] We present the first case report of a congenital AVM presenting as a mass near the junction of superior vena cava (SVC) and right atrium (RA) in an asymptomatic 62-year-old female with no history of any hereditary hemorrhagic telangiectasia.
A 62-year-old woman was referred to our institution for assessment of a cardiac murmur. A transthoracic echocardiogram (TTE) documented a 3.8 cm × 2.3 cm mass in the SVC, near the junction of the SVC and RA. Turbulent flow was seen in the SVC with a peak velocity of 1.38 m/s. Computed tomography scan chest with contrast confirmed the mass, but it was unclear whether the mass was due to a proteinaceous cystic mass or a soft tissue mass, based on density measurements. Cardiac magnetic resonance imaging confirmed the TTE findings [Figure 1] and also confirmed that this was an enhancing soft tissue mass rather than a cystic mass. She subsequently underwent SVC resection and reconstruction with a #19 mm ringed Gore-Tex graft. Her postoperative course was unremarkable and she was discharged home. | Figure 1: High fluid content or blood products within the mass. High fluid content or blood products within the mass axial T2 weighted fat saturated magnetic resonance imaging (level of the main pulmonary artery [MPA]) shows a homogeneously T2 hyperintense mass (*), posterior to the ascending aorta (Ao) and intimately associated with the anterior wall of the superior vena cava (SVC) (white arrow). The SVC is compressed by the mass. LA = left atrium. T2 hyperintense signal can be seen with cystic lesions; and possibly with solid asses with blood products or high fluid content
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The surgical specimen was a soft, nodular looking lesion measuring 2.5 cm × 3.0 cm × 1.5 cm. One side of the specimen abutted the SVC and was attached to a rim of fat connected to a portion of RA. Histologic findings showed a vascular structure with large dilated vascular spaces lined by endothelial cells and filled with red blood cells, while a few vascular spaces showed organizing thrombus. Some papillary lesions with cord like structures lined by endothelial cells were also seen. These findings were seen against a background of fibrous or spindle cell stroma rich in mucopolysaccharide. Large feeding vessels were seen on the epicardial surface. The pathologic features were those of an AVM of the SVC [Figure 2] and [Figure 3]. | Figure 2: Microscopy shows large dilated vascular structures lined by endothelial cells filled with red blood cells and occasional organizing thrombus (black arrow). Some papillary structures are seen (white arrow). The background is composed of fibrous or spindle cell stroma rich in mucopolysaccharides (asterisk). The mass is attached to the right atrium (RA) (H and E; original magnification: ×2.5)
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 | Figure 3: Dilated vascular channel (Bv) with fibrous stroma (asterisks) (Movat Pentachrome; original magnification: × 10)
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Mediastinal AVM was first described by Lunde et al. and is more common in infancy and childhood. [1],[2] Congenital mediastinal AVM is rarer, and often discovered at postmortem or incidentally on radiologic imaging. Most case reports of mediastinal AVM, document cases in the posterior mediastinum, with only two and one case(s) in the anterior and middle mediastinum respectively. [2],[3],[4] In the English language literature, Gutierrez et al. have reported three cases of AVM in infants, which involved the branches of brachiocephalic vessels and SVC system. [5]
To the best of our knowledge, this is the first case report of an AVM in an asymptomatic adult arising as a mass lesion at the junction of SVC and RA. Given that our patient had no risk factors that would predispose her to the development of an AVM, her lesion is likely congenital.
 References | |  |
| 1. | Lunde P, Sörlie D, Bolz KD, Eide TJ. Huge arteriovenous malformation in the mediastinum. Clinical presentation and surgical management. Scand J Thorac Cardiovasc Surg 1984;18:75-80. 
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| 2. | Tennyson C, Routledge T, Chambers A, Scarci M. Arteriovenous malformation in the anterior mediastinum. Ann Thorac Surg 2010;90:e9-10.
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| 3. | Walklin RP, Entwisle J, Cheung YK, Dayal V. Pulmonary arteriovenous malformation: A rare anterior mediastinal mass. J Med Imaging Radiat Oncol 2012;56:545-7.
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| 4. | Rajiah P, Kanne JP. Mediastinal vascular malformation presenting with stroke. Br J Radiol 2010;83:e138-42.
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| 5. | Gutierrez FR, Monaco MP, Hartmann AF Jr, McKnight RC. Congenital arteriovenous malformations between brachiocephalic arteries and systemic veins. Chest 1987;92:897-9.
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Correspondence Address:
Jagdish Butany
Department of Pathology 11th Floor, 11E-420, Toronto General Hospital, 200 Elizabeth Street, Toronto, ON M5G 2C4
Canada
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0377-4929.134758
[Figure 1], [Figure 2], [Figure 3] |
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