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Ann Thorac Surg 2005;80:1521-1523
© 2005 The Society of Thoracic Surgeons

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Case report

Of Buffaloes, Horseshoes, and Having No Connections

^a Department of Surgery, University of North Carolina, Chapel Hill, North Carolina
^b Division of Cardiothoracic Surgery, University of North Carolina, Chapel Hill, North Carolina

Accepted for publication April 12, 2004.

^_* Address reprint requests to Dr Detterbeck, Division of Cardiothoracic Surgery, University of North Carolina, CB 7065, Medical School Wing C, Room 354, Chapel Hill, NC27599-7065 (Email: fdetter{at}med.unc.edu).

	Abstract

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We report a patient with multiple congenital pulmonary anomalies, including unilateral pulmonary artery agenesis with an atretic left lung, "buffalo chest," and a variant of the anatomic anomaly "horseshoe lung," discovered during double lung transplantation. Both hemithoraces were filled by the right lung. The right chest was occupied primarily by the anatomic right lower lobe, and the left chest by the right middle lobe at the apex and the anatomic right upper lobe at the base.

	Introduction

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Lack of separation of the lung occupying the right and left hemithoraces and anomalies of development of the mediastinal pleural membranes separating the thorax into two distinct pleural spaces are rare anomalies, as is unilateral agenesis of the pulmonary artery. When encountered, such conditions can cause confusion for surgeons and radiologists who are trying to define the anatomy.

A 25-year-old man with cystic fibrosis (CF) and a forced expiratory volume in 1 second of 19% was listed for lung transplantation. His past medical history had been typical for CF with multiple antibiotic treatment courses for recurrent pulmonary infections. His chest radiograph demonstrated the typical appearance of CF lungs. An echocardiogram was normal except for mild right ventricular hypertrophy. A quantitative perfusion scan attributed 81% of the pulmonary perfusion to the right and 19% to the left lung.

Bronchoscopy at the time of intubation for transplantation revealed no endobronchial abnormalities. After bilateral anterior thoracotomy incisions it became apparent that there was no pleural separation between the right and left thoracic spaces. This was presumed to be due to a congenital absence of the mediastinal pleural reflection, a rare anomaly known as "buffalo chest." However, the fissures of the right and left lungs were unusual. Even after division of the sternum, the anatomy of the lungs remained utterly confusing until it was realized that the right lung was shaped like a horseshoe and filled both the right and left hemithoraces. Most of the right hemithorax was occupied by the right lower lobe. The right middle lobe was deformed and partially straddled the upper mediastinum, although most of this lobe occupied the upper portion of the left hemithorax. The right upper lobe was completely on the left side and upside down, with the apical segment extending into the left costophrenic sulcus (Fig 1).

View larger version (141K): [in this window] [in a new window]   Fig 1. Herniation of the right lung across the anterosuperior mediastinum into the left base. (RUL = right upper lobe; RML = right middle lobe; RLL = right lower lobe.)

A right lung transplant was performed in a standard fashion. On the left side, the atrial anastomosis was enlarged by opening the native left atrium beyond the cuff created by the small pulmonary veins. The donor left PA was sewn to an opening created on the left side of the main PA. A routine end-to-end left bronchial anastomosis was performed. The donor's left and right lungs filled each hemithorax normally. There was nothing unusual about the patient's postoperative course, and he continues to do well 7 years after the transplant.

	Comment

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Buffaloes have no mediastinal pleura separating the thoracic cavity into two pleural spaces. Thus an arrow could cause a bilateral pneumothorax, which is thought to account for the ease with which Indians could kill these creatures. This anatomic variant has been described in humans [1], specifically in several patients with horseshoe lung and no pleural separation in the region of the connecting isthmus of lung parenchyma [2–5]. However it has not been linked to CF or unilateral pulmonary artery agenesis.

Horseshoe lung typically involves a posterior mediastinal connection between the basal segments of the left and right lungs [2]. This has been described in 46 patients (list of references available on request), none of which involved an anterior connection. However, 2 of the patients had posteroapical connections, involving a parenchymal isthmus joining the apical regions of the left and right lungs behind the esophagus [4], or herniation of a portion of the right upper lobe into the left midhemithorax [5]. Hypoplasia of one lung was seen in 48% of patients (22 of 46) with horseshoe lung. This generally involves right lung hypoplasia and the "scimitar" syndrome. None of these cases involved a hypoplastic lung.

Approximately 40% of the cases of horseshoe lung have involved abnormalities of the right or left PA. Horseshoe lung was associated with left PA atresia in 1 patient who had a hypoplastic left lung fed by small collateral vessels arising from the main and the right PA. An abnormally lobulated portion of the right lower lobe herniated across the midline behind the heart to occupy the left lower hemithorax [6].

Unilateral pulmonary artery agenesis has an estimated incidence of 1 in 150,000 [7], although this is difficult to establish because 30% of patients with unilateral pulmonary artery agenesis are asymptomatic [8]. It is often associated with other cardiovascular anomalies. The presenting symptoms are nonspecific, including recurrent pulmonary infections, decreased exercise tolerance, mild dyspnea on exertion, and occasionally hemoptysis and pulmonary hypertension.

This case is unusual for several reasons. First, it represents a constellation of rare abnormalities (CF, buffalo chest, unilateral pulmonary artery agenesis, hypoplastic left lung, and contralateral mediastinal lung herniation) that have not previously been reported together. The herniation of the lung across the anterosuperior mediastinum, with an upside-down position in the opposite chest, has not previously been reported. It is also remarkable that radiographs, bronchoscopy, and echocardiogram did not suggest an abnormality. Finally, it appears that these anomalies did not cause significant symptoms as this patient's clinical course was entirely consistent with worsening CF.

Our patient did not have a true buffalo chest; rather, he had functionally united hemithoraces as a result of the herniated right lung and the atretic left lung. A similar case of buffalo chest involved a left lung that herniated partially across the anterosuperior mediastinum 17 years after a right pneumonectomy [1]. Our patient also did not have a typical horseshoe lung with an inferoposterior connection between the right and left lungs. We believe that horseshoe formation of one lung, anterosuperior herniation, and rotation of the apical RUL into the left costophrenic sulcus have not been reported. Thus, this case involved a situation where hoofbeats did not indicate the presence of horses, or even buffaloes, but a heretofore unknown beast.

	References

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1. Grathwohl KW, Derdak S. Images in clinical medicine. Buffalo chest N Engl J Med 2003;349:1829.[Free Full Text]
2. Spencer H. Pathology of the lungOxford, NY: Pergamon Press; 1968.
3. Frank JL, Poole CA, Rosas G. Horseshoe lungclinical, pathologic, and radiologic features and a new plain film finding. AJR Am J Roentgenol 1986;146:217-226.[Abstract/Free Full Text]
4. Manner J, Jakob C, Steding G, Fuzesi L. Horseshoe lungreport on a new variant—"inverted" horseshoe lung—with embryological reflections on the formal pathogenesis of horseshoe lungs. Ann Anat 2001;183:261-265.[Medline]
5. Clements BS, Warner JO. The crossover lung segmentcongenital malformation associated with a variant of scimitar syndrome. Thorax 1987;42:417-419.[Abstract/Free Full Text]
6. Ersoz A, Soncul H, Gokgoz L, et al. Horseshoe lung with left lung hypoplasia Thorax 1992;47:205-206.[Abstract/Free Full Text]
7. Bouros D, Pare P, Panagou P, Tsintiris K, Siafakas N. The varied manifestation of pulmonary artery agenesis in adulthood Chest 1995;108:670-676.[Abstract/Free Full Text]
8. Ten Harkel AD, Blom NA, Ottenkamp J. Isolated unilateral absence of a pulmonary arterya case report and review of the literature. Chest 2002;122:1471-1477.[Abstract/Free Full Text]

This article has been cited by other articles:

				J. Groarke, D. Breen, F. O'Connell, and R. O'Donnell Bilateral pneumothorax resulting from a diagnostic thoracentesis Eur. Respir. J., November 1, 2007; 30(5): 1018 - 1020. [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Alden M. Parsons Frank C. Detterbeck Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Parsons, A. M. Articles by Detterbeck, F. C. Search for Related Content PubMed PubMed Citation Articles by Parsons, A. M. Articles by Detterbeck, F. C.