Segmental bronchial atresia-Case Report

History- 42y female with cough & fever of recent onset presented for CECT chest for evaluation of focal opacity in chest X ray (radiograph not available). Case Submitted by Dr MGK Murthy, Dr GA Prasad

CECT findings show-

Lobulated hypodense ( avg. HU of about 28) nonenhancing soft tissue density lesion in the apicoposterior segment of left upper lobe of lung the thin branchings of the lesion in the superior & posterior margins suggesting the CT- finger in glove appearance. No fat density or any calcifications seen in the lesion. Adjacent vessels are displaced by the lesion without any filling defects in them. Perilesional area of air trapping & oligemia seen in the lung parenchyma.  No adjacent bronchiectasis is seen separately. Segmental bronchus of apicposterior segment of left upper lobe is seen for very small length with markedly smaller  caliber near origin & not seen in rest of the course.

-findings are consistent with Segmental bronchial atresia of apicoposterior segmental bronchus of left upper lobe with distal bronchocele / mucocele with surrounding air trapping & oligema.

Discussion –

-        Bronchial atresia usually is benign and asymptomatic and is incidental finding & clinical manifestations may range from recurrent pulmonary infections to mild wheezing and dyspnea. Bronchial atresia is a congenital abnormality resulting from focal interruption of a lobar, segmental, or subsegmental bronchus with associated peripheral mucus impaction (bronchocele, mucocele) and associated hyperinflation of the obstructed lung segment.  The apicoposterior segmental bronchus of the left upper lobe is most common site to be involved, followed by segmental bronchi of the right upper, middle, and lower lobes.

-        As the bronchial pattern is entirely normal distal to the site of stenosis, it has been suggested that the atresia is probably not a result of abnormal growth and development, but rather secondary to a traumatic event during fetal life like  intrauterine ischemia.

-        Distal hyper-inflation in lung is caused by collateral ventilation through intraalveolar pores of Kohn, bronchoalveolar channels of Lambert, and interbronchiolar channels. Interbronchiolar channels, which connect terminal bronchioles from adjacent lung segments, may be the major conduit of collateral ventilation, because the pores of Kohn and channels of Lambert have not consistently been found in infants. 

-        A classic radiographic finding of bronchial atresia is a branching tubular or nodular area of increased opacity that extends from the hilum with surrounding hyperlucent lung parenchyma. CT is the most sensitive imaging modality, and when findings are typical, they may be considered diagnostic in most cases. CT shows the lack of communication between the mucocele and hilum & can show smaller mucoceles not seen at conventional radiography, and is more sensitive in demonstrating segmental hyperinflation, associated mass effect, and possible calcification. CT is useful in depicting the absence of vascularity and enhancement within the lesion and may help exclude a vascular cause

-        Differential diagnosis includes allergic bronchopulmonary aspergillosis, cystic fibrosis, or any lesion that causes bronchial narrowing and thus mucus impaction. The presence of a mucocele with adjacent hyperinflation helps narrow the differential diagnosis.

-        The majority of patients are asymptomatic and therefore no treatment is necessary. Surgical excision should be reserved for patients with complications secondary to the atretic bronchus, such as infection or significant compromise of adjacent lung parenchyma. Lobar resection and segmentectomy have been used, however the ultimate goal is to preserve as much normal lung parenchyma as possible to maintain pulmonary function.