2024 Volume 27 Issue 2 Pages 92-97
A 35-year-old woman who had been treated for systemic lupus erythematosus presented with coughing and slight fever that had persisted for two weeks. Computed tomography of the chest revealed a mass-like infiltrate as well as cystic lesion in the right upper lobe with a defect of the posterior segmental bronchus, and antibiotic treatment was initiated. On detecting a deteriorating infiltrate with fluid retention in the cyst a week later, we performed bronchoscopic examination and identified the absence of the orifice of the right posterior segmental bronchus, leading to a diagnosis of congenital bronchial atresia. Although the infiltrate improved with the administration of other antibiotics, considering the possibility of recurrent infection in the future, we performed thoracoscopic segmentectomy. Due to the fact that antibiotic treatment for obstructive pneumonia with bronchial atresia is sometimes difficult, it is important to determine appropriate timing for surgical resection of the affected segment.
先天性気管支閉鎖症は，胎生期に何らかの原因により気管支が閉鎖した状態である．健診など無症状で発見される場合が多いが，肺炎を発症すると難治性である．症例は35歳女性．2週間ほど前より咳嗽，微熱が持続するため当院総合内科を受診した．胸部CT検査で右肺上葉に浸潤影を認め，また，右B2区域気管支の閉鎖を疑った．当院呼吸器内科で肺炎として抗菌薬加療が開始された．1週間後の胸部CT検査で肺炎の増悪を認め，精査目的に気管支鏡検査が行われた．右B2区域気管支の閉鎖を認め，先天性気管支閉鎖症の診断となった．抗菌薬加療を継続し，肺炎は軽快したが陰影は一部残存しており，また，今後感染を繰り返す可能性を考慮し，胸腔鏡下右S2区域切除術を施行した．先天性気管支閉鎖症を背景とする肺炎の抗菌薬治療は難渋することがある．症例に応じた適切な抗菌薬治療と手術タイミングの選択が重要である．
Congenital bronchial atresia (CBA) is a rare pulmonary abnormality caused by obstruction of the bronchus during embryonic development.1-3 This condition can lead to retention of bronchial secretion distal to the obstructed lesion and emphysematous changes in peripheral lung tissues.3-5 CBA is often found incidentally on chest X-ray in asymptomatic individuals,3, 5 but is sometimes complicated with obstructive pneumonia refractory to antibiotic treatment, and surgery may be indicated for selected patients.3, 5-7
Here, we report a case of refractory pneumonia in an adult woman who had been treated for systemic lupus erythematosus. Imaging studies and bronchoscopy revealed that the patient developed obstructive pneumonia in the setting of CBA. She underwent thoracoscopic segmentectomy of the affected lung segment, and her postoperative course was uneventful.
A 35-year-old woman, who had no history of pulmonary disease, made an outpatient visit to the Department of General Internal Medicine of our hospital with a cough and low-grade fever that had persisted for two weeks. She had been taking 5 mg of prednisolone for systemic lupus erythematosus. Chest computed tomography (CT) showed a mass-like shadow in the posterior segment (S2) of the right upper lung and cystic lesion extending to the dorsal side of the tracheal bifurcation (Figure 1A, B). The orifice of the right posterior segmental bronchus (B2) could not be identified, and the corresponding pulmonary parenchyma was distended. Obstruction of B2 due to mucus retention or defect of B2 was suspected. Laboratory tests revealed a white blood cell count of 8,970/µL and C-reactive protein (CRP) concentration of 1.67 mg/dL. Amoxicillin and potassium clavulanate were initially administered orally. Chest contrast-enhanced CT a week later revealed that the mass-like shadow had increased in size with cystic fluid retention (Figure 1C, D).
A mass-like shadow in S2 of the right upper lung (red arrow) and cystic lesion extending to the dorsal side of the tracheal bifurcation (yellow arrow) (A, B). The mass-like shadow increased with cystic fluid retention (red and yellow arrows) (C, D). The infiltrative and mass shadows decreased before surgery (E, F).
The patient was admitted to our hospital for further evaluation and treatment. Fiberoptic bronchoscopy revealed that the orifice of B2 was not present, leading to a diagnosis of CBA (Figure 2). Treatment with ampicillin-sulbactam was followed by piperacillin-tazobactam, but this was discontinued due to drug allergy. The antibiotic was switched to meropenem, and CRP decreased to < 0.05 mg/dL. However, the mass-like shadow remained (Figure 1E, F).
The right upper lobe bronchus bifurcated into two segmental branches, and the orifice of B2 (white arrow) could not be detected.
The patient underwent thoracoscopic lung resection 35 days after admission because of possible recurrence of pneumonia. The posterior interlobar fissure between S2 and adjacent segments were adherent, probably due to inflammation. While an ascending branch of the right pulmonary artery was detected and resected, a branch of B2 was not detected. Segmentectomy of S2 was successfully performed with resection of the cystic lesion. The operative time was 181 minutes, with blood loss of 125 mL. No bacterial growth was noted on culture of the cystic fluid. The pathological findings revealed the dilated bronchi, severely collapsed scar-like tissue extending from the surrounding alveolar regions to interlobular septa, and chronic inflammatory cell infiltration within the remaining air spaces (Figure 3A, B). The cysts consisted of bronchial tissue with thickened smooth muscle layers. These findings were consistent with bronchial atresia accompanied by fibrosis and obstructive pneumonia. Antibiotics were continued for three days after surgery. The postoperative course was uneventful, and she was discharged on postoperative day 7 (Figure 4). The patient’s condition was favorable two months after surgery, with no recurrence or complications.
Macroscopic pathological image: Dilated bronchi in the lung (red arrow) (A). Microscopic pathological image (20×): Chronic inflammatory cell infiltration around the bronchi and collapsed alveoli (B).
The residual lung was well-inflated with no remaining infiltration of pneumonia.
Bronchial atresia was first reported by Ramsey et al. in 1953, characterized by expanded alveoli and complete obstruction of the inlet orifice.1 CBA is considered to be caused by obstruction of the bronchial artery during the fetal period.2 There are theories suggesting that vascular supply problems occur between the 5th and 15th weeks of embryonic development3 or after the 16th week, i.e., after completion of the bronchial tree.2 Previously, CBA was considered to be a subtype of congenital cystic lung disease. However, recent findings suggest that the pathological features of type 2 congenital pulmonary airway malformation (CPAM) are similar to those of CBA, leading to a tendency to equate CBA with type 2 CPAM.8
Meng et al. reported that CBA most frequently occurs in the left upper lobe, followed by right upper lobe, and more common in segmental or subsegmental bronchi than in lobar ones.3, 9 In patients with CBA, collateral ventilation through Kohn’s pores and canals of Lambert causes overinflation of the lung distal to the obstructed bronchus, leading to emphysematous changes. Mucoceles are also observed distal to the atretic bronchus. CT typically reveals ectatic bronchi, emphysematous alveoli, and mucous retention.4 In addition to these findings, the diagnosis can be confirmed if bronchoscopic examination reveals bronchial obstruction or a defect. However, Wang et al. reported that only 50% of patients with CBA can be diagnosed based on bronchoscopy.5
CBA is usually asymptomatic and found incidentally. However, when pneumonia occurs in patients with CBA, obstruction of the sputum clearance pathways makes healing difficult and can lead to recurrence. It has been reported that the normal lung surrounding the CBA lesion may become compressed or pulmonary hypertension may develop in the long term.10, 11 There are no clear guidelines for CBA treatment, and it remains controversial. There are case reports of asymptomatic patients being monitored,6 while some reports recommend surgery to avoid compression or damage to adjacent lung parenchyma.7 Additionally, surgical resection may be suggested for cases in which pneumonia recurs or cannot be cured with pharmacological treatment, and the possibility of malignant lesions cannot be ruled out.5
In this case, CT showed a typical image of CBA with segmental bronchial obstruction, obstructive pneumonia, and parenchymal cysts. Fiberoptic bronchoscopy was useful for definitive diagnosis. There was no history of pneumonia, but the patient had underlying systemic lupus erythematosus with long-term prednisolone administration, which could lead to recurrent pneumonia if the involved lung is not radically resected. Since it is a benign condition, it is essential to carefully determine the timing of intervention to ensure adequate resection with sufficient preoperative administration of antibiotics.
We described a case of surgically treated CBA. Surgical treatment was safe and curatively effective. The timing of surgery should be carefully considered, taking into account the patient's overall health status and control of infection.
The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
