Horseshoe lung: Differential diagnosis

Abstract

A detailed radiologic and anatomic study of one horseshoe lung syndrome has already been published from this centre. A further case of horseshoe lung, which was also diagnosed prospectively by radiology, is described. Alongside, this is a set of a group of three conditions: we describe a right accessory lung with a peculiar feeding arterial branch originating from the left basal pulmonary artery. The bronchogram and oesophagogram of this case were normal. The other is a case of bridging bronchus where the left lower lobe bronchus originates from the right main stem bronchus. This was discovered at post mortem bronchogram performed on a 19 weeks foetus. Finally, in the dog, we found that the pulmonary angiogram and bronchogram display close similarity to human horseshoe lung though the dog has two separate lungs. The common denominator of all above cases is the presence of a pulmonary arterial branch or bronchus crossing the midline from the ipsi to the contralateral side. Therefore, it may be concluded "in contradiction to the common belief" that pulmonary angiography or bronchography alone is not sufficient for the diagnosis of horseshoe lung. When only one of these investigations is available, computerized tomography is necessary to show the isthmic lung tissue before the diagnosis of horseshoe lung is confirmed.

Clinics in diagnostic imaging (173)

“…A parietal pleural defect allows for direct or indirect adherence of lung parenchyma through the intervening visceral pleura. (11) The isthmus of normal lung tissue lies posterior to the pericardial sac but anterior to both the oesophagus and aorta. Unilateral pulmonary hypoplasia is a constant feature of horseshoe lung and the bronchovascular supply to the isthmus is usually from the hypoplastic lung.…”

A 30-year-old female presenting with fever, cough and purulent sputum, and suffering from recurrent pulmonary tuberculosis

“…Bridging bronchus is usually detected during the neonatal period and is indicated by recurring atelectasis, pneumonia, bronchiectasis, chronic ventilation-perfusion mismatch, pulmonary oedema and respiratory failure [2][3][4][5][6][7][8][9]. These problems are usually caused by chronically inadequate pulmonary drainage and ventilation problems.…”

“…These problems are usually caused by chronically inadequate pulmonary drainage and ventilation problems. Bridging bronchus is also often associated with a sling pulmonary artery and, occasionally, with congenital heart disease [2,5,6,8,[10][11][12].…”

“…Bridging bronchus is a congenital anomaly, first described as a large bronchial branch originating from the left main stem bronchus and spanning across the mediastinum from left to right, before entering the contralateral lung, as reported here [1][2][3][4][6][7][8].…”

“…Less frequently, it is reported as a bronchial branch that crosses the mediastinum from right to left, in the opposite direction [6,9]. There has been one report describing a braided bronchus, in which the trachea and left bronchial tree were structurally normal and the right mainstem bronchus branched directly into four distinct segments [5].…”