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CASE REPORT
 

UNUSUAL CAUSE OF WIDE MEDIASTINUM:
BILATERAL ANEURYSM OF INNOMINATE VEINS
 

K.C.Garg, M.D.; Venkatraman Bhat, M.D.; Rajendra Kumar M.D.;
Department of Radiology, Hamad Medical Corpotation , Doha, Qatar

Introduction

Aneurysm of innominate veins is a very rare anomaly of the systemic veins. Incidental observation of such pathology leads may to misinterpretation of the initial radiographic study and mistaken radiological diagnosis of more common entities. Modern imaging with helical computed tomography (CT), gadolinium enhanced magnetic resonance imaging (MRI) with advanced post-processing techniques almost always lead to correct diagnosis. Awareness of this entity widens the horizon of differential diagnosis. We report a case of bilateral aneurysm of innominate veins diagnosed by contrast enhanced spiral computed tomography.

Case presentation

A 42-year-old male patient was referred for computed tomography of the chest. He had presented at the Tuberculosis Center at Rumaillah Hospital with a history of irritant cough. The chest x-ray showed widening of the mediastinum which was presumed to be tuberculous lymphadenopathy. The laboratory tests were reportedly equivocal and the AFB of sputum was negative. The patient was empirically put on antitubercular therapy for two months without improvement of cough. Lack of response and persistent, unchanged, mediastinal widening prompted referral for contrast enhanced computed tomography of the chest.

CT examination of the chest revealed mediastinal widening due to aneurysmal dilatation of the right and left innominate veins. Dilatation of the right innominate was fusiform whereas the left innominate vein showed a saccular form of dilatation. There was no evidence of thrombosis or narrowing of the lumen. The rest of the venous system and airways were normal. Multiplanar and three-dimensional capability of spiral CT was helpful for conclusive demonstration of the anomaly.

Discussion

Venous aneurysms are rare lesions. The most frequently involved vessels are the jugular veins, the deep veins of the extremities, and the portal vein. Aneurysms of the mediastinal veins and abdominal veins other than the portal vein are much more infrequent.
Congenital aneurysms of innominate veins are rare anomalies of the venous system with four previously reported cases in the English literature1. The lesion may be incidentally detected and occasionally mistaken for more commonly encountered pathology leading to patient mismanagement. In our case, precise diagnosis was of great importance as patient was initially managed with empirical anti-tubercular treatment. Contrast enhanced CT or Gadolinium enhanced MR imaging are mainstays in the diagnosis of this condition. Complications of venous aneurysm are thrombosis, stenosis, rupture and distal embolisation. Indications for surgery are controversial2. One report recommends aggressive management with succular aneurysms3. On the other hand, another study recommends non-surgical conservative management, as the disorder is asymptomatic and has good prognosis2.
In conclusion, venous aneurysm should be considered in the differential diagnosis of m2ediastinal widening. Differentiation of venous aneurysms from other mass lesions is important to avoid biopsy or plan surgery, if surgery is attempted. Correct diagnosis can be achieved non-invasively with dynamic contrast-enhanced CT or three-dimensional contrast enhanced magnetic resonance angiography.¨

References:

1. Gu¨ney B, Demirpolat G, Savas¸ R, Alper H. An unusual cause of mediastinal widening: bilateral innominate vein aneurysms. Acta Radiol 2004;45:266–268.
2. Yokomise H, Nakayama H, Aota M, Daitoh N, Katsura H (1990) Systemic venous aneurysms. Ann Thorac Surg 50:460–462.
3. A. Tsuji,1 Y. Katada,1 M. Tanimoto,1 I. Fujita2 Congenital Giant Aneurysm of the Left Innominate Vein .Is Surgical Treatment Required? Pediatr Cardiol 25:421–423, 2004.