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Journal of Postgraduate Medicine, Vol. 55, No. 3, July-September, 2009, pp. 204-205 Images in Pathology Missed aortic dissection - The Class 3 lesion Vaideeswar P, Patil LY, Mishra P1 Departments of Pathology (Cardiovascular & Thoracic Division), Cardiovascular & Thoracic Surgery 1, Dr. PK Sen, Seth G. S. Medical College and K. E. M. Hospital, Mumbai - 400012, India Date of Submission: 22-Aug-2008 Code Number: jp09062 PMID: 19884749 DOI: 10.4103/0022-3859.57405 A 29-year-old male with Marfan syndrome was admitted for progressively increasing shortness of breath and palpitations for two months. On echocardiography there was severe aortic regurgitation and global hypokinesia (left ventricular ejection fraction of 15%). The dimensions at the aortic valvular regions were as follows: aortic annulus 32 mm, intersinus distance 53 mm, sinotubular junction 50 mm and ascending aorta 50 mm. The patient underwent Bentall procedure. The aortic semilunar cusps, received separately, appeared translucent, stretched with rolled free margins. Three transversely-oriented intimal tears, measuring 2.2 x 0.3, 1.8 x 0.3 and 0.4 x 0.2 cm, respectively, were noted in the two resected flaps of the ascending aorta, associated with adventitial bulges [Figure - 1]. There was no evidence of rupture. The intima was pale yellow and smooth. The tears revealed the walls to be composed of loose fibrocellular tissue and remnants of medial lamellar elastic units with a minor degree of undermining of the adjacent intima [Figure - 2]. There was significant aortopathy in the form of elastic tissue loss and fragmentation, medionecrosis and increased collagenization [Figure - 2]; only small foci of increased ground substance were noted. Discussion The young man in the reported case had Marfan syndrome, a heritable autosomal-dominant disorder. It results from mutations in the genes coding for fibrillin-1, an integral component of elastin.[1] As a consequence, there is alteration in the quantity and quality of elastin, manifesting as a multisystemic disorder. Of clinical consequence is the involvement of the cardiovascular system, where abnormal aortic elasticity leads to aortic regurgitation and/or aneurysm.[2] Both features were present in the case presented. A more ominous complication is aortic dissection (AD), which has been traditionally classified on the basis of the extent of aortic involvement i.e. the Debakey and Stanford classifications.[3] The European Society of Cardiology classification has categorized AD into Classes 1 to 5, depending on the pathogenetic mechanisms.[4] Class 3 lesion has been described as "a stellate or linear intimal tear associated with exposure of underlying aortic media or adventitial layers" and importantly devoid of "progression and separation of the medial layers".[5] This description aptly fits with the gross morphology of the ascending aorta excised in this patient. These subtle forms of dissection are unusual and rare, discovered incidentally as they are not discernible on the current noninvasive imaging modalities such as transesophageal echocardiography, computed tomography or even cardiac magnetic resonance imaging; these Class 3 lesions are best picked up by aortography.[5] Alterations in the structure of the aortic media, as evident in our case, lead to dilatation of the aorta. Being less distensible, the intima tears-that leads to the more common Class 1 lesion or the classic AD and less often to Class 3 or limited AD. Though appearing innocuous, such intimal tears can sooner or later predispose to acute AD. In addition, due to the thinness of the wall, there can be seepage of fluid with pericardial effusion or rupture with hemopericardium. To prevent this dismal prognosis, it would be important to suspect this lesion in all patients with risk factors for aortic dissection, presenting with acute aortic syndromes, but without classic imaging characteristics. References
Copyright 2009 - Journal of Postgraduate Medicine The following images related to this document are available:Photo images[jp09062f2.jpg] [jp09062f1.jpg] |
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