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A pulmonary azygos lobe encountered during thoracotomy for modified Blalock-Taussig shunt

Frank Edwin, Baffoe Gyan, Mark Mawutor Tettey, David Kotei, Kwabena Frimpong-Boateng

National Cardiothoracic Centre, Korle Bu Teaching Hospital, PO Box KB 846, Korle Bu, Accra, Accra, KB 846, Ghana

Correspondence to:
Frank Edwin, fedwin68{at}yahoo.com

A 3-year-old boy was scheduled for a modified Blalock-Taussig shunt (MBTS) on account of tetralogy of Fallot. A right posterolateral thoracotomy was used. On entering the chest, a "fourth lung lobe" was found (fig 1) medial to a pleural fold extending from the apex of the right hemithorax towards the hilum of the lung with the azygos vein lodged in the lower free border of this "pleural mesentery" (fig 2). These findings were consistent with a pulmonary azygos lobe and its associated four-layered pleural fold referred to as the mesoazygos. The mesoazygos was resected together with the azygos vein to gain access to the mediastinum and the MBTS was successfully performed. Recovery was uneventful.

View this figure (115K): in this window | in a new window | PowerPoint for Teaching   Figure 1 *Azygos vein in the free border of the mesoazygos; # the azygos lobe as it passes behind the mesoazygos.

 

View this figure (112K): in this window | in a new window | PowerPoint for Teaching   Figure 2 The mesoazygos is seen after "delivering" the azygos lobe from behind it.

 

A pulmonary azygos lobe is usually an incidental finding in cadaver dissections and chest radiography. Its bronchial supply is derived from a branch of the upper lobe bronchus and not as a separate branch from the right main bronchus. Therefore, it is not an additional or fourth lobe. The surgical importance of this anomaly is the restricted access to the mediastinum and to the azygos lobe, and the hazards this poses during surgery and especially during video-assisted thoracoscopic surgery.^1,2

Competing interests: none.

Patient consent: Patient/guardian consent was obtained for publication.

1. Asai, K, Urabe, N, & Takeichi, H. Spontaneous pneumothorax and a coexistent azygos lobe. Jpn J Thorac Cardiovasc Surg 2005; 53: 604–6.[CrossRef][Medline]
2. Smith, J, Karthik, S, & Thorpe, JAC. Pulmonary azygos lobe: a potential obstacle during thoracoscopic sympathectomy. Eur J Cardiothorac Surg 2004; 25: 137.[Free Full Text]

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