A 68-year-old, well-developed, well-nourished black male presents to the emergency department complaining of shortness of breath. He denies chest pain. He has no significant past medical history and takes no medications. A chest x-ray shows clear lung fields, mild cardiomegaly and a widened thoracic aorta with linear calcifications. An MRI of the chest shows aortic dilatation in the thorax, extending proximally, with atrophy of the muscularis and wrinkling of the intimal surface. What is the most likely etiology of this condition?

A. Atherosclerosis

B. Hypertension

C. Marfan's syndrome

D. Syphilis infection

E. Takayasu's arteritis

  The correct answer is D. Although rare now because of advances in treatment, syphilitic aortitis and aneurysm are still seen, especially in underserved populations. This complication generally occurs 10 to 40 years after initial infection. The vasa vasorum of the aorta undergoes obliterative endarteritis, leading to atrophy of the muscularis and elastic tissues of the aorta and dilatation. Linear calcifications are often seen in the ascending aorta by x-ray. The intimal wrinkling or "tree barking" is also a common feature. Syphilitic aneurysm can be associated with respiratory distress, cough, congestive heart failure and rarely, rupture.

Atherosclerosis (choice A) is the most common cause of aortic aneurysms. These are most often located in the abdominal aorta, distal to the renal arteries. Intimal wrinkling and linear calcifications are not seen.

  Hypertension (choice B) is usually responsible for dissecting aneurysms located within 10 cm of the aortic valve. Patients present with sudden chest pain, which is usually severe and tearing in nature. The chronic hypertension causes a cystic medial necrosis, allowing the separation of vessel layers.

  Marfan's syndrome, an autosomal dominant connective tissue disorder (choice C) is also associated with dissecting aneurysms, usually of the ascending aorta. The patients are often

very tall with arachnodactyly and ligamentous laxity. Their life-span is generally shortened.

This patient's description and age are not consistent with this diagnosis.

Takayasu's arteritis (choice E) is a syndrome characterized by ocular disturbances and weak

pulses in the arms. It occurs most frequently in young females. It is considered a giant cell

arteritis, and does not cause aneurysms.

  一位68歲發(fā)育營養(yǎng)良好的黑人男性以呼吸急促為主訴送往急診科。他沒有特殊的醫(yī)療史和用藥史。胸片顯示肺野清晰，輕度心臟擴大和擴張的邊緣鈣化的胸主動脈。胸部MRI顯示胸主動脈擴張，向近心端擴展，伴有肌層萎縮和內(nèi)膜皺褶。最可能的病因是？

A.動脈粥樣硬化

B.高血壓

C.馬凡綜合征

D.梅毒感染

E.大動脈炎

  正確答案是D。盡管因為治療的進步梅毒已經(jīng)非常罕見，梅毒性主動脈炎和梅毒動脈瘤仍存在，特別是在一些資源匱乏的人群中。這種綜合征常在初次感染的10至40年后發(fā)病。主動脈的外膜滋養(yǎng)血管發(fā)生閉塞性血管炎，導致肌層和動脈彈力組織萎縮以及主動脈擴張。X光片也經(jīng)?？吹缴鲃用}邊緣鈣化。內(nèi)膜皺褶或“樹膠樣腫”也是常見的特征。梅毒性動脈瘤可導致呼吸疾病，咳嗽，充血性心力衰竭以及罕見的動脈瘤破裂。

動脈粥樣硬化（選項A）是主動脈瘤最常見的原因，他們通常發(fā)生于腹主動脈，腎動脈的遠端。內(nèi)膜皺褶和邊緣鈣化不會發(fā)生。

高血壓（選項B）通常與距主動脈瓣10厘米以內(nèi)的夾層動脈瘤有關(guān)。表現(xiàn)為突發(fā)胸痛的病人通常病情嚴重且動脈瘤已破裂。慢性高血壓則導致動脈中膜囊性壞死，從而使血管壁分離。

馬凡綜合征（選項C），是一個與夾層動脈瘤有關(guān)的常染色體顯性遺傳結(jié)締組織疾病，他的動脈瘤通常發(fā)生在升主動脈。該病病人通常身材高挑，指（趾）細長，韌帶松弛。他們的壽命通常是縮短的。該病例中病人的描述和年齡與馬凡綜合征的診斷不符。

大動脈炎（選項E）是以視力障礙和上肢脈搏減弱為特征的綜合征。通常發(fā)生于年輕女性。它被認為是巨細胞動脈炎的一種，通常不會造成動脈瘤。