Clinical History
A 42-year-old man, smoker without respiratory symptoms, presented with episodes of intense cramping pain in hypogastrium that usually lasted a few seconds and spontaneously yielded. He had recently been diagnosed with ileitis.
Imaging Findings
Imaging for investigation of acute abdominal pain was undertaken. These included a posteroanterior chest radiograph.
An oval or slightly tubular cylindrical opacity was seen in the right upper lung zone. A subtle hyperlucent area surrounded the opacity (Figure A). Bronchial mucus plug and bronchial atresia was suspected as the patient had no respiratory symptoms. A chest CT was performed in order to confirm this suspicion and to exclude the presence of a solitary pulmonary nodule or endobronchial lesion taking into account the smoking history of the patient (Figure B).
CT revealed a tubular hypodense lesion extending cephalad from the hilum with marked hypodensity in the surrounding lung located in the right upper lobe (Figure C, D). A cul-de-sac appearance was seen at the end of the sacular lesion. No signs of endobronchial tumour, foreign body or proximal stricture were seen. No other anomalies were seen.
Discussion
Bronchial atresia is a rare congenital abnormality characterised by focal interruption of the proximal lumen of a bronchus. It is associated with mucus impaction (bronchocele) and peripheral hyperinflation of the distal lung segment, due to collateral air drift [1-3].
Some authors have reported that it is more common in young men [1].
As in the presented case, bronchi of the upper lobes are more often involved than those of the lower lobes [4]. The exact cause is unknown [1].
Histologic findings vary depending on whether there is an infection distal to the atretic bronchus. Microscopic analysis typically reveals intact distended alveoli, a finding indicative of lobar hyperinflation [4]. The proximal blind-ending bronchus is used as a diagnostic macroscopic indicator. Mucocele is characteristically found just distal to the atresia. Surrounding lung parenchyma appears normal or hyperinflated [1].
Bronchial atresia is usually asymptomatic and incidentally discovered. If symptomatic, clinical manifestations may be related to pulmonary infections [4].
A classic radiographic finding is a well-defined branching tubular or nodular area of increased opacity that extends from the hilum surrounded by hyperlucent lung parenchyma. [4]
CT is the most sensitive imaging modality and its characteristic findings include mucocele, occlusion of the bronchus central to the mucocele and surrounding areas of air trapping. CT scan on expiration confirms the air-trapping. The diagnosis is confirmed if all three are present and acquired proximal bronchial obstruction by tumour, foreign body or inflammatory stricture is excluded [1, 2]. As opposed to other authors we think that fiberoptic bronchoscopy is not usually needed because identification of a blind-ending bronchus can be easily made with CT [1].
CT and MRI are useful in depicting the absence of vascularity and enhancement within the lesion and exclude a vascular cause [4].
Radiography and CT can be useful in the follow-up of these patients [3].
Differential diagnosis includes other causes of mucous impaction like bronchiectases (allergic bronchopulmonary aspergillosis, cystic fibrosis), bronchial strictures or endobronchial tumours. Other anomalies such as bronchial cysts, intralobar sequestration or cystic adenomatoid malformation may present with low attenuation but do not maintain a close relation with the bronchus and do not have either a cul-de-sac appearance or air trapping [1, 4].
Most cases do not necessitate surgery because bronchial atresia is a benign disease, asymptomatic with no other serious complications. Minimal invasive surgery should be reserved only for patients with serious complications [1, 4]. The major indication for surgery is recurrent infection [2].
Differential Diagnosis List
Bronchial atresia.
Bronchiectasies
Endobronquial tumours
Bronchial cysts
Intralobar sequestration
Adenomatoid malformation
Congenital lobar emphysema
