Extralobar pulmonary sequestration

Clinical History

33 Years old patient (smoker) with progressive pain in the left lateral chest wall. The patient reported similar problems four years ago.

Imaging Findings

A 33-year-old patient was admitted to the hospital with progressive pain in the left lateral chest wall. He was a smoker (one package a day) until one and a half year ago. The symptoms were augmented by deep breathing and by moving. Four years ago he had similar problems. A CT-scan of the thorax was done four years ago. A paravertebral mass was found above the diaphragm on the left hemithorax, which was suspected to be a lung sequestration. No specific treatment was offered to him. In the last few months the pain was permanently present which required intermittent Paracetamol or Mefenamin Acid treatment. Additionally, the patient suffered from reflux symptoms approximately once a month since several years. X-ray of the thorax and CT were performed. The X-ray showed a paravertebrally and retrocardially located mass on the left side in a. p.- projection. In Side projection no abnormalities were seen. CT (Somatom VolumeZoom, Siemens, Erlangen, Germany, collimation 4x2.5 mm, 120 ml contrast media, 2 ml/sec flow, 55 sec delay), revealed an centrally hypodense lesion in paravertebral location on the left side. Two arties originating from the descending aorta were located : One smaller artery originating ventrally and one larger originating laterally on the left side. Venous drainage was shown to take place via an accessory hemiacygos vein into the left subclavian vein. In lung window settings the extrapleural location of the lung sequestration was evident showing additionally an accessory interlobar fissure seen in the lower lobe. Video-assisted thoracoscopic exploration was performed showing an extralobar lung sequester. There were two arteries originating directly from the descending aorta. These arteries were clipped and the sequestration was completely resected thoracoscopically. The patient was discharged on the fifth postoperative day after an uneventful course. The histopathological assessment showed a lung sequestration without evidence of malignancy.

Discussion

A pulmonary sequestration is a rare acquired (mostly intralobar) or congenital (intralobar or extralobar) abnormality characterized by the presence of pulmonary tissue that does not communicate with the normal tracheo-bronchial tree. Pulmonary sequestrations can be divided into two types : the more common intralobar and the rare extralobar type. Both types of sequesters receive its arterial supply from an anomalous systemic artery, most common from the thoracic aorta or its branches (3). Intralobar sequesters are located within the normal lung and its pleural cover. A pulmonary venous drainage is typical. The most common clinical manifestation is infection. There is no sex predelection. Intralobar sequesters are in 60-70% of cases located on the left side. 98% occur in the lower lobes. They appearance on plain chest radiographs as consolidations. They are have more often ill-defined margins. Uncomplicated lesions are uniformly dense in chest radiographs. Overlaying infection may cause focal changes in density including fluid-gas levels as a consequence of fistula formation with adjacent bronchi. In CT both intralobar as well as extralobar sequestrations show typically tissue inhomogenity. Extralobar sequesters are located extrapleurally and are characterized by a venous drainage via thoracic or abdominal systemic veins. Atypical types of drainage such as drainage to the portal vein have been reported (4). Extralobar sequestrations are more often associated with other congenital malformations (congenital diaphragmatic hernia, congenital heart disease, etc.) (4). They are mostly diagnosed as incidental findings. Male patients are more often affected (M:F=4:1). They are in 90% of cases located on the left side. Clinical manifestations as a result of recurrent infection (current case) or hemorrhage (1) are less common. Presentation of extralobar sequesters in chest radiography differs from intralobar sequesters by better defined outer marigins and a greater variety in location. They may occur in a variety locations in- and outside the lung such as pericardial space, mediastinum or retroperitoneum. In paramediastinal location they show a well-defined outer margin (due to the pleural cover) and abut the the mediastinum medially such that they are radiographically difficult to differentiate from mediastinal masses (present case). Multiple imaging modalities including chest X-ray, bronchoscopy, CT and MRI was recently proposed for preoperative assessment of pulmonary sequestration (5). However, the present case shows that MDCT alone may provide full diagnostic information necessary for planning surgery. Vascular supply was in the present case correctly assessed by CT. Multiplanar reconstruction may be helpful in demonstration of the vascular supply showing the entire course of anomalous vessels in one secondary image.

Differential Diagnosis List

Final Diagnosis

extralobar pulmonary sequestration

URL:	https://www.eurorad.org/case/727
DOI:	10.1594/EURORAD/CASE.727
ISSN:	1563-4086