Teaching Case

A 44-years-old female patient with a clinically suspected asthma and smoking habits underwent a clinical examination due to periods of mild shortness of breath, a chest radiograph was requested followed by a contrast enhanced chest-CT.

The radiographic study showed a branching tubular opacity extending from the left hilum into the left upper lobe, a hyperlucency of the right upper lobe was also noted (Fig. 1).

Contrast-enhanced CT of the chest was performed to further characterise the previously described radiographic findings.

A non-enhancing tubular mass (finger-in-glove appearance) was seen extending cephalad from the left hilum, with surrounding hypoattenuating pulmonary parenchyma of the apicoposterior segment of the left upper lobe (Figs. 2 and 3). No other pulmonary abnormalities were noted.

Bronchial atresia is a rare congenital abnormality of unknown cause resulting from focal interruption of a lobar, segmental or subsegmental bronchus [1].

The apicoposterior segmental bronchus of the left upper lobe is the most commonly involved, being also the affected segment in this clinical case [2].

The proximal blind-ending bronchus is usually associated with mucus impaction (mucocele) distal to the atresia point, where the adjacent lung parenchyma may appear normal or hyperinflated. These findings are responsible for the hilar mass-like shadow appearance on radiographs [2,4].

On chest radiographs and CTs, an hyperlucent / hypoattenuating lung surrounding the mucocele represents a combination of air trapping and focal parenchymal oligemia, which is secondary to a combination of intrapulmonary vascular compression and hypoxic vasoconstriction [1,4].

Patients are usually asymptomatic, but mild symptoms may be present such as recurrent pulmonary infections, mild wheezing or dyspnoea [1].

Imaging characteristics are the key for the diagnosis with CT being one of the most sensitive methods.

The classic radiographic appearance is a branching tubular or nodular hypotransparent area that extends from the hilum with surrounding hyperlucent lung parenchyma.

Differential diagnoses include vascular anomalies or other abnormalities with mucus impaction, such as bronchial cyst, pulmonary embolism, bronchiectasis or intralobar sequestration. On contrast-enhanced CT, it is possible to rule out vascularity / enhancement within the branching hilar lesion helping to exclude a vascular or tumoral cause for the findings. Intralobar sequestration and bronchial cysts are rarely associated with hyperlucency surrounding the mass. In doubtful cases acquired proximal bronchial obstruction by tumour, foreign body or inflammatory stricture can be excluded by bronchoscopy [3].

Nowadays, bronchial atresia is considered a benign pathology that usually doesn’t require treatment (it is reserved for patients with complications such as infection). To prevent complications, surgical resection used to be performed in most patients. However, this subject remains controversial [1,5].

In conclusion, bronchial atresia is a rare benign congenital disease resulting from focal interruption of a lobar, segmental or subsegmental bronchus. Correct diagnosis is usually possible with contrast-enhanced chest CT. As bronchial atresia is a benign disease usually without other serious implications, most cases will not necessitate surgery. Thus, a correct diagnosis becomes particularly important [3].

Written informed patient consent for publication has been obtained.