Intralobar pulmonary sequestration associated with an aneurysmal aberrant aortic branch

Abstract

43-year-old woman, with no prior history of significant medical disease, presented with persistent vague chest discomfort and cough. A chest x-ray film showed a calcified mass in the left lower lobe, compatible with old granulomatous disease (Figure 1, A). However, a subsequent computed tomographic (CT) scan of the chest revealed a low-density lesion within the left lower lobe (Figure E1) with no evidence of surrounding parenchymal consolidation. A large feeding vessel, 2.5 cm in diameter, with a diffusely calcified wall was noted to arise from the lower thoracic aorta (Figure 1, B). Its course was better delineated on sagittal images and with a 3-dimensional reconstruction of a CT angiogram (Figures E2 and 2, A). The lower lobe mass had venous drainage to the left atrium. This anatomic relationship was compatible with an intralobar pulmonary sequestration. The patient underwent a left thoracotomy. There was no surgical plane between the mass and the surrounding left lower lobe. The diagnosis of intralobar sequestration was confirmed by the intralobar position of the mass, a systemic arterial feeding vessel, and normal pulmonary venous drainage. After suture closure of the large feeding vessel (Figure 2, B), a standard resection of the left lower lobe containing the sequestration completed the procedure. The postoperative course was uneventful, and the patient was discharged on the fifth postoperative day. Clinical Summary Pulmonary sequestration is a congenital abnormality characterized by a bronchopulmonary segment with an anomalous systemic arterial blood supply. There are two variants: intralobar and extralobar. The former is a lung segment contained within the normal visceral pleura and pulmonary parenchyma. In extralobar sequestration, the bronchopulmonary tissue is outside the visceral pleura and may be contained in its own pleural envelope. Intralobar sequestration is most frequently diagnosed in the pediatric population and shows equal gender prevalence. It is rarely found in patients aged above 40 years. 1,2 In the adult population, this lesion must be distinguished from the far more common neoplastic lesions, especially bronchogenic carcinoma. Up to 15% of patients, particularly in the adult population, do not have symptoms when the sequestration is discovered. 3 Presentation varies from the incidental finding of a mass in an asymptomatic patient to symptoms of recurrent bronchitis or pneumonia. The diagnosis is usually obtained by CT scan, and the anatomy may be better defined using CT angiography or magnetic resonance angiography. The pathogenesis of sequestration is the result of an accessory lung bud that develops from the ventral primitive foregut as it migrates caudally and receives systemic arterial supply instead of the normal pulmonary arterial supply. Some authors maintain that intralobar sequestration in older adults represents an acquired lesion related to bronchial obstruction, pneumonia, pulmonary