During gestation, the trachea and esophagus originate from a common foregut, but they later divide into separate pathways. If there are any developmental issues in the foregut, it can result in defects like atresias, webs, and esophageal lung or bronchus (7).
The development of the human lung and tracheobronchial tree begins around 26 days after conception with the appearance of the respiratory diverticulum or lung bud. This bud is a ventral outpouching from the endodermal foregut and serves as the precursor for the entire epithelial lining of the tracheobronchial tree. (1) The vascular interstitium of the lung, supporting cartilage, and pleural investments are derived from mesodermal tissue. The development of the lung bud is initiated by reciprocal induction of the splanchnic mesoderm, triggered by the accumulation of retinoic acid. As development progresses, the lung sacs grow around the esophagus, and the tracheobronchial tree comes into contact with the esophagus. The exact cause of congenital bronchopulmonary foregut malformations (CBPFMs) is still unclear, but an accepted theory is that there is a defect in the manner by which the developing lung bud meets with the developing esophagus. (2)
CBPFM may occur when aberrant lung tissue becomes separated from the rest of the lung and trachea during the elongation of the esophagus. It has been observed in an adriamycin-induced rat model of esophageal atresia, indicating a potential common cause between CBPFM and esophageal atresia (8).
CBPFM is a rare birth defect where there is an abnormal connection between the esophagus or stomach and a part of the respiratory system. This condition can present in various forms, such as an esophageal bronchus or an esophageal lung (11).
The esophageal lung is an uncommon birth defect characterized by the main bronchus originates from the esophagus instead of the usual location at the carinal bifurcation. This condition, known as a variant of communicating bronchopulmonary foregut malformations, often results in a hypoplastic lung. Patients with esophageal lung often have nonspecific symptoms that can mimic other lung diseases, but recurrent pneumonia after feeding is a common indication. Esophageal lung can be associated with other congenital anomalies such as VACTERL, pulmonary artery sling, esophageal atresia, duodenal atresia, and laryngeal cleft. (13)
CBPFM, was first described in 1968 (3) and an anatomical classification was proposed in 1992 (4). In 1992, a classification system was proposed to categorize CBPFM into four groups based on related defects and the level of communication. Group I is associated with esophageal atresia and tracheoesophageal fistula, with two subdivisions based on the extent of lung involvement. Group II is characterized by the absence of a mainstem bronchus and communication between the sequestered lung and the lower esophagus. Group III involves an isolated part of the lung communicating with the esophagus, while Group IV involves communication between a normal bronchial system and the esophagus. The most common communications are between the mid or distal third of the oesophagus and the right lower lobe (43%), left lower lobe (22%) or RMB (10%). CBPFM is difficult to diagnose early due to its rarity and nonspecific symptoms and can occur at any age but is typically detected several months after birth. The most common symptoms include chronic cough, recurrent pneumonia, hemoptysis, vomiting, and respiratory distress. (16) Misdiagnosis is common, with 84% of cases initially being operated for tracheoesophageal fistula and esophageal atresia. (4) Coexistence of esophageal atresia and dextrocardia is rare and poses challenges for surgery. (5) The common associated anomalies were cardiovascular, skeletal and anorectal components in a VACTERL association (vertebral defects, anal atresia, cardiac def`ects, tracheo-oesophageal fistula, renal anomalies, and limb abnormalities), diaphragmatic hernia and other anomalies involving the duodenum, stomach, ribs and vertebrae. (6)
CBPFMs are similar to pulmonary sequestration, with the bronchus supplying lung tissue that is missing from the normal tracheobronchial tree. Some CBPFMs also have connections with the lower esophagus or stomach. The blood supply to these lesions may be abnormal, often being augmented or replaced by a systemic artery from the aorta. Anomalous pulmonary venous drainage may also be present. (3)
Diagnosis of CBPFM can be challenging, especially when it is obscured by the presentation of esophageal atresia/tracheoesophageal fistula. Unilateral lung collapse, with or without esophageal atresia/tracheoesophageal fistula, should raise suspicion of CBPFM. Upper gastrointestinal imaging is the first choice for evaluation but the value was limited in group I due to atresia of the proximal esophagus. In this circumstance, bronchoscopy and chest CT scan should be considered. (9)
A chest CT scan is essential in identifying the vascular supply and drainage of the lungs, detecting airway malformations, and assessing parenchymal disease. Virtual bronchoscopy (VB) is a diagnostic tool that has several advantages over traditional bronchoscopy, such as not requiring general anesthesia and specialized expertise. It has potential diagnostic applications in various conditions, including broncho-esophageal fistulas, post-lung transplantation anastomosis, suspected foreign body aspiration, and inhalation injuries. However, VB has some limitations, such as its inability to detect small mucosal lesions and the exposure of patients to radiation. It also cannot determine mucosal architecture, vascularity, color, and may result in false positive findings due to secretions and artifacts. (14)
Currently, surgery is the only treatment option available for Communicating Bronchopulmonary Foregut Malformation (CBPFM), with thoracoscopic therapy showing promising results. Early and accurate diagnosis is crucial for successful recovery in neonatal cases (17). Unilateral lung resection in neonates and infants is generally well-tolerated, but the long-term consequences, such as chest wall deformation, scoliosis, and postpneumonectomy syndrome, are not clear (12). Reconstruction of the esophageal bronchus is another option for managing this condition and is preferred as it preserves the affected lung and prevents complications associated with pneumonectomy. The first successful reconstruction of the bronchus was reported in 1997. (10). Therefore, attempts to reconstruct the bronchus should be limited to stable patients with non-infectious lungs and after ruling out significant associated malformations.
Post-pneumonectomy syndrome is a complication characterized by mediastinal shift and obstruction of airways and blood vessels that can occur months or years after pneumonectomy. It is more common in infants who have undergone right pneumonectomy due to the rapid growth of their thoracic cage. Treatment typically involves correcting the mediastinal shift by installing an expandable prosthesis prophylactically or therapeutically. (15)