Arterial Aneurysm in Anomalous Vessel

Anu Bansal, MD - Case Coordinator
Cheryl Ann Sadow, MD - Radiology Discussion
Kimberley M Springer, MD - Pathology Discussion
Philip Costello, MD - Attending Radiologist
Pablo R Ros, MD, MPH - Attending Radiologist

June 9, 2003

Presentation

Imaging Findings

Frontal and lateral radiographs demonstrate normal lung volumes and slight irregularity of the left hemidiaphragm; a vague opacity is visible posteriorly on the lateral view. Computed tomography and MRA show a curvilinear vessel with peripheral calcifications in the right lung base. The vessel appears to originate at the aorta and is enlarged. This suggests sequestration. An aneurysmal feeding vessel is extremely uncommon.

Diagnosis

Discussion

A morphological abnormality is immediately apparent in the gross lung sample. The aneurysmal vessel dominates the cut section (post-fixation). A microscopic image of the vessel wall demonstrates the calcifications, while a second image of the lung parenchyma demonstrates focal, non-necrotizing granulomas. The anomalous artery entered the lung at a distal point consistent with abnormal entry of a vessel originating from the aorta. This feature is usually seen in intralobar sequestration, but the typical chronic inflammation and parenchymal lesions of sequestration are not present. The rare peribronchiolar granulomas may indicate impaired airway clearance and hypersensitivity reaction, consistent with a forme fruste of sequestration wherein the bronchial communication is almost intact.

Radiology Discussion:

Pulmonary sequestration is an anomaly of tracheobronchial branching characterized by the retention of an embryonic systemic arterial supply, usually via a branch of the aorta. It is more commonly intralobar, sharing pleura with adjacent lung. Less commonly, the sequestration is extralobar, having a separate pleural covering.

Intralobar sequestration is not typically diagnosed until adulthood and is usually discovered after recurrent infections. Sixty percent of intralobar sequestrations occur in the left base and 40% in the right. Intralobar sequestrations drain via the pulmonary veins. Extralobar sequestration is typically diagnosed in the neonate due to association with other congenital abnormalities, such as congenital heart disease. Ninety percent occur in the left base. Extralobar sequestrations drain via systemic veins (e.g., azygos). They are frequently asymptomatic.

Pulmonary sequestration can often be diagnosed from the prenatal ultrasound which will show an echogenic lung mass. Sequestrations may regress completely in utero . The diagnosis can be made with US, CT, or MR by demonstrating a systemic arterial supply to a lung consolidation or mass in the lower lobes. If recurrent infections are a problem, the sequestration can be resected.

References

Zylak CJ, Eyler WR, Spizarny DL, Stone CH. Developmental lung anomalies in the adult: radiologic-pathologic correlation. Radiographics. 2002 Oct; 22 Spec No:S25-43.

Lopoo JB, Goldstein RB, Lipshutz GS, Goldberg JD, Harrison MR, Albanese CT. Fetal pulmonary sequestration: a favorable congenital lung lesion. Obstet Gynecol. 1999 Oct;94(4):567-71.

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