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Cases
An Asymptomatic Posttraumatic Lung Lesion
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Background
A 70-year-old man is referred for evaluation of a left lower lobe opacity observed on routine radiographs (see arrowheads in Image 1A-B). He smokes cigarettes but has no complaints of chest pain, shortness of breath, dyspnea, or hemoptysis. At 22 years of age, he underwent surgical repair of damage to his left diaphragm caused by a fall from a bridge when he was 7 years old.
His vital signs are normal. Blood pressures in his arms are equal, and pulses in his extremities are equal and within the reference range. A bruit is noted in the lower left posterior aspect of this chest wall and loudest adjacent to his left thoracotomy scar. No tenderness, palpable thrill, or pulsatile mass is present. The remaining cardiovascular findings are normal. The patient has no digital clubbing or cyanosis and no peripheral edema or palpable venous clots. A chest CT is performed (see Image 2).
What is the diagnosis?
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down for Hint and Answer
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***** HINT *****
Chest CT scans depict an enlarged, tortuous vessel along the posterior aspect of the chest wall.
***** ANSWER *****
Posttraumatic arteriovenous fistula between the ninth intercostal artery and ninth intercostal vein: The posttraumatic systemic arterial–to–systemic venous fistula is a well-known consequence of penetrating injuries to the human body. The most common sites for this vascular complication are the extremities and the neck (Robbs, 1994; Yilmaz, 1997).
Systemic arterial–to–systemic venous fistulas of the thorax are rare but might be expected to occur after penetrating or blunt injury to the thoracic cage. When these posttraumatic thoracic fistulas do occur, the great vessels or the subclavian vessels are typically involved. In rare cases, the internal mammary artery is involved.
Although injuries to the chest wall are common, intercostal arteriovenous fistulas are unusual (Sastic, 1984). However, seemingly insignificant injuries to the chest wall can cause thoracic systemic arterial–to–systemic venous fistulas. For example, intercostal fistulas have been reported after minor invasive procedures, such as pleural biopsy and thoracentesis (Lai, 1990; Derdeyn, 1993; Saito, 1975; Howell, 1991). This current patient had an intercostal artery–to–intercostal vein fistula. Whether his fistula was due to his fall during childhood or the later surgical intervention is not known.
Because traumatic injury causes most systemic arterial–to–systemic venous fistulas, they are generally recognized early and treated expeditiously (Yilmaz, 1997). However, as this case demonstrates, a fistula may persist for years without consequence to the patient. Precise indications for intervention in such chronic thoracic fistulas have not been established (Fein, 1983). Because this patient was asymptomatic, no intervention was undertaken.
For more information on arteriovenous fistulas, see the eMedicine articles Arteriovenous Fistulas (within the Internal Medicine specialty) and Vascular Anomalies (within the Radiology specialty).
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References
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Derdeyn CP, Middleton WD, Allen BT, et al. Acquired intercostal arteriovenous fistula: color doppler ultrasonographic diagnosis. J Ultrasound Med 1993; 12:679-681.
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Fein AB, Godwin JD, Moore AV, et al. Systemic artery-to-pulmonary vascular shunt: a complication of closed-tube thoracostomy. AJR Am J Roentgenol 1983; 140:917-919.
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Howell JB. Intercostal arteriovenous fistula due to pleural biopsy. Thorax 1991; 46: 688.
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Lai JH, Yan HC, Kao SJ, et al. Intercostal arteriovenous fistula due to pleural biopsy. Thorax 1990; 45:976-978.
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Robbs JV, Carrim AA, Kadwa AM, et al. Traumatic arteriovenous fistula: experience with 202 patients. Brit J Surg 1994; 81:1296-1299.
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Saito T, Matsuda M, Yamaguchi T, et al. A case of traumatic systemic-pulmonary arteriovenous fistula. Jpn Heart J 1975; 16:196-203.
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Sastic LM, Mansoory A, Hossain Z. Traumatic intercostal arterio-venous fistula with pseudoaneurysm: a case report. Del Med J 1984; 56:581-583.
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Yilmaz AT, Arslan M, Demirkilic U, et al. Missed arterial injuries in military patients. Am J Surg 1997; 173:110-114.
Author:
Ryland P. Byrd, Jr, MD, Chief of Pulmonary Medicine, Medical Director of Respiratory Therapy, Quillen Mountain Home Veterans Affairs Medical Center, Professor, Department of Internal Medicine, Division of Pulmonary Diseases and Critical Care Medicine, James H. Quillen College of Medicine, East Tennessee State University, and Thomas M. Roy, MD, Chief, Division of Pulmonary Diseases and Critical Care Medicine, Professor of Medicine, Department of Internal Medicine, James H. Quillen College of Medicine, East Tennessee State University
eMedicine Editor:
Sat Sharma, MD, Associate Professor, University of Manitoba, Department of Medicine, Division of Pulmonary Medicine
Source
http://emedicine.com
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