An Unusual Cause of Large Thrombosed Pulmonary Artery Aneurysms Associated with Chronic Thromboembolism

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1 CSE REPORT n Unusual Cause of Large Thrombosed Pulmonary rtery neurysms ssociated with Chronic Thromboembolism Chen-Te Wu, Kun-Eng Lim 1 Department of Radiology, Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Radiology 1, uddhist Tzu Chi General Hospital, Taipei ranch, Taipei, Taiwan STRCT We present a rare case of unilateral multiple large thrombosed pulmonary artery aneurysms that occurred in the course of chronic pulmonary thromboembolism in a 51-year-old man. Chest radiography showed multiple rounded opacities in the right hilar and parahilar regions. CT scans showed marked aneurysmal dilatation of the segmental and lobar branches of the right pulmonary artery containing large thrombi. This pattern of pulmonary artery aneurysms has not been previously reported. (Tzu Chi Med J 2006; 18: ) Key words: pulmonary artery aneurysm, chronic thromboembolism, computed tomography INTRODUCTION Pulmonary artery aneurysms (Ps) are rare abnormalities of pulmonary arteries [1,2] which are usually caused by infection or trauma, or are seen in association with congenital heart disease or ehcet's disease [3-8]. To the authors' knowledge, multiple Ps due to chronic pulmonary thromboembolism (PTE) have never been reported in the English literature. We report on a patient with Ps caused by chronic pulmonary embolism. CSE REPORT 51-year-old man went to a community hospital with a cough, chest pain, and dyspnea for 4 days. Computed tomography (CT) of the chest revealed acute pulmonary embolism involving the right pulmonary artery. Thus, he was referred to our hospital for further treatment. He had neither fever nor hemoptysis, but he was dyspneic in our emergency room. The remainder of the physical examination was normal. The blood pressure was in the normal range. rterial blood gas analysis on room air showed an oxygen tension of 82.4%, PaCO2 of 38.2 mmhg, and ph of 7.4. Electrocardiography revealed a normal pattern. His past medical history showed that he was a long-term smoker without systemic disease. Chest radiography in the ER showed no definite abnormality. Peripheral venous doppler sonography revealed no deep vein thrombosis in the lower limbs. Transthoracic echocardiography showed mild tricuspid valve regurgitation and mild pulmonary artery hypertension (31 mmhg). Laboratory results of D-dimers, homocysteine, coagulation factors, tumor markers, serum chemistry, and routine complete blood count (including WC differential count) were within the normal ranges. pulmonary function test revealed mild restrictive ventilatory impairment. n intravenous infusion of heparin (20000 U/day until mean acti- Received: ugust 19, 2005, Revised: October 17, 2005, ccepted: November 30, 2005 ddress reprint requests and correspondence to: Dr. Kun-Eng Lim, Department of Radiology, uddhist Tzu Chi General Hospital, Taipei ranch, 289, Jianguo Road, Xindian, Taipei, Taiwan OMR

2 C. T. Wu, K. E. Lim vated partial thromboplastin time value) was given for thrombolysis. Three days after admission, magnetic resonance (MR) imaging of the chest was obtained to follow-up the condition of the thrombus (Fig. 1). fter the optimal anticoagulation status (prothrombin time 4 mean normal value, international normalized ratio 3.70) had been achieved and his symptoms had improved, he was discharged and followed up in our out-patient department. fter discharge, symptoms such as exertional dyspnea and chest pain fluctuated. Follow-up serial chest radiographs showed multiple, slowly enlarging, rounded or ovoid opacities in the right hilar and parahilar regions. Two chest CT scans (3 months and 8 months after the episode) demonstrated marked aneurysmal dilatation of the right pulmonary artery and its lobar and segmental branches with large intraluminal thrombi (Fig. 2-4). Follow-up transthoracic echocardiography showed that the tricuspid valve regurgitation and pulmonary artery hy- pertension (32 mmhg) were still present. Suboptimal anticoagulation, mild dyspnea, dry cough, and hemoptysis were noted 8 months after the episode of acute pulmonary embolism. The patient refused operative embolectomy. fterwards the patient was lost to follow-up. DISCUSSION Pulmonary artery aneurysm (P) is rare [1,2] and its etiologies are numerous [3]. The pathogenesis of P is not completely clear and it may be caused by various conditions such as congenital or acquired heart disease (left-to-right shunting, post-stenotic dilatation), infection (tuberculosis, syphilis, pneumonia), connective tissue disorders (Marfan's syndrome, Ehlers-Danlos syndrome), collagen vascular diseases, direct or blunt trauma, and systemic vasculitis (Hughes-Stovin's Fig. 1. C fifty-one-year-old man had a sudden onset of cough, chest pain, and dyspnea 7 days before MR imaging. MR angiography of the chest without and with Gd- DTP enhancement shows high signal intensity lesions in the right main pulmonary artery with extension to its proximal branches in T1-weighted and T2- weighted images, which are compatible with pulmonary embolism. focal lesion of high signal intensity in the periphery of the 6 segment of the right lower lobe may be due to a small pulmonary infarction. () xial T1-weighted image. () xial T2-weighted image. (C) Coronal T1WI with Gd-DTP enhanced image. OMS

3 Fig. 2. Three months later, axial chest CT without and with enhancement shows thrombi of different densities involving the right main pulmonary artery and lobar arteries. In the lung window, an opacity in the periphery of the right upper lobe could be due to pulmonary infarction or a small pulmonary hemorrhage (rrow). The calibers of the right main and lobar pulmonary arteries are within the normal ranges. () xial chest CT with enhancement. () Lung window. Fig. 3. Seven months after the episode, a chest roentgenogram shows multiple ovoid well-defined densities in the right hilar and parahilar regions. disease, ehcet's diseases) [4-12]. The clinical presentation and natural course vary with the etiology. Symptoms associated with P include exertional dyspnea, hemoptysis, cough, and chest pain or tightness [2]. In contrast, our patient mainly suffered from external dyspnea and chest pain during the development of the Ps. Most patients who survive acute pulmonary embolism completely recover. However, some patients have recurrent PTE or survive with residual thromboembolic burden. The residual thromboembolic burden will evolve into chronic PTE. In chronic PTE, the organized thrombi are not amenable to thrombolysis and cause decreased perfusion in the pulmonary vascular bed. Thus chronic thromboembolic pulmonary hypertension and right heart failure ensue [13,14]. The chest radiographic findings of Ps include pulmonary nodules or dense focal consolidation [2,15]. These nodules may be either well-defined or poorly defined due to associated hemorrhage. Focal consolidation may evolve into a nodule or mass [16]. Sometimes Ps present as an enlarged hilar opacity and simulate hilar lymphadenopathy; misinterpretation may cause unnecessary and invasive studies such as bronchoscopy, angiography [15,16], or CT-guided biopsy. Noninvasive imaging studies such as contrast-enhanced CT [17,18] and MR imaging [18,19] can not only confirm aneurysmal dilatation of the pulmonary artery but also detect other pulmonary vascular lesions such as thromboembolism. Contrast-enhanced spiral CT angiography of the pulmonary circulation is a useful, noninvasive diagnos- OMT

4 C. T. Wu, K. E. Lim Fig. 4. Eight months after the episode, axial chest CT without and with enhancement shows marked aneurysmal dilatation of the right pulmonary artery and its lobar and segmental branches with large intraluminal thrombi. () xial chest CT without enhancement. () xial chest CT with enhancement. tic imaging modality and it has gained increased acceptance as a first-line study in the diagnostic workup of pulmonary vascular lesions. Ps are shown as enhancing rounded opacities that are isodense to the central pulmonary arteries [20]. In our patient, the aneurysmal dilated pulmonary arteries presented as unilateral hilar and parahilar opacities on chest radiographs and contained large thrombi shown in the contrast-enhanced spiral CT scan. In one study, CT had a 78% sensitivity and a 100% specificity in the diagnosis of surgically resectable chronic PTE [21]. Chronic PTE is diagnosed on contrast-enhanced CT by visualization of eccentric thrombi within the pulmonary arteries (with or without calcification), or by indirect signs, such as irregularities in the arterial walls, abrupt narrowing of the arterial diameter, abrupt cut-off of distal lobar or segmental artery branches, or vascular distortion, strictures, and webs [22]. In our patient, the right main pulmonary artery was occluded by thrombi, which had no enhancement on dynamic enhanced MR images in the initial episode. Thus, the possibility of tumor emboli and pulmonary artery sarcoma was excluded. Intraluminal thrombi filled the right main pulmonary artery as well as the lobar and segmental branches with aneurysmal dilatation, as demonstrated in two CT scans done at a 5 month interval, confirming the diagnosis of chronic pulmonary thromboembolism and pulmonary artery aneurysms. lthough the patient was lost to follow-up, serial chest radiographs and CT scans proved the relationship between pulmonary artery aneurysms and chronic pulmonary thromboembolism. There are reports of small pulmonary artery aneurysms associated with acute pulmonary embolism or pulmonary thromboembolism of uncertain duration, demonstrated by chest radiographs, V/Q scans, CT, and angiography [2,9,23]. Our diagnosis was proved by serial chest radiographs and spiral CT scans. In summary, large thrombosed pulmonary artery aneurysms associated with chronic pulmonary thromboembolism is an unusual presentation and, as far as we know, has not been reported in the English literature. Differential diagnoses of the etiology of pulmonary aneurysm should include this entity under appropriate clinical settings. REFERENCES 1. Lopez-Candales, Kleiger RE, leman-gomes J, Kouchoukos NT, otney MD: Pulmonary artery aneurysm: Review and case report. Clin Cardiol 1995; 18: Chung CW, Doherty JU, Kotler R, Finkelstein, Dresdale : Pulmonary artery aneurysm presenting as a lung mass. Chest 1995; 108: Muller Nestor: Radiologic diagnosis of disease of the chest. Philadephia: W Sauders Company, 2001, pp Vaideeswar P, Deshpande JR: Pulmonary artery aneurysms. Int J Cardiol 1992; 35: aum D, Khoury GH, Ongley P, Swan HJ, Kincaid OW: Congenital stenosis of the pulmonary artery branches. Circulation 1964; 29: Deterling R Jr, Clagett OT: neurysm of the pulmonary artery: Review of the literature and report of a case. m Heart J 1947; 34: Tung HL, Liebow : Marfan's syndrome; observations at necropsy: With special reference to medionecrosis of the great vessels. Lab Invest 1952; 1: Slavin RE, de Groot WJ: Pathology of the lung in ehcet's disease. Case report and review of the literature. m J Surg Pathol 1981; 5: Pereira de Godoy JM, atigalia F: ilateral pulmonary OMU

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