Bronchogenic Cyst as an Unusual Cause of a Persistent Cough and Wheeze in Children: A Case Report and Literature Review

Wheezing and cough are common case scenarios that pediatricians encountered in their office practices. Although a bronchogenic cyst is an uncommon condition, it is essential to be considered in the differential diagnosis of a chronic cough and wheezing among young children who fail to respond to appropriate medical treatment. A 28-month-old girl was referred to our pediatric pulmonology clinic with persistent symptoms of a cough and wheeze unresponsive to standard asthma therapy. This presentation prompted us to undertake a detailed diagnostic evaluation. The evaluation exposed a cystic mass in the middle mediastinum compressing the trachea and left main bronchus. The cyst was excised and confirmed pathologically to be a benign bronchogenic cyst. Subsequently, the patient recovered well and had been free of respiratory symptoms during follow-up visits. This report highlights one of the rare causes of wheezing and cough in young children and emphasizes the importance of considering it in the differential diagnosis of a child presenting with refractory asthma-like symptoms. This is important for early diagnosis and management and to avoid unpredictable complications of this treatable condition.


Introduction
e common symptoms of asthma in children include a cough, wheeze, and breathing di culties. If these symptoms persist over a period of asthma therapy or the symptoms are not typical for asthma, additional evaluation is strongly recommended.
Bronchogenic cysts (BCs) are a rare congenital malformation of the foregut that is typically found in the mediastinum [1]. A ected patients can present with symptoms that are related to their compressive e ect and irritation of the surrounding structures [2]. We report on a child who presented with persistent wheeze and cough, not responding to medical treatment. Further investigation revealed that the cause of this child's symptoms and signs was a bronchogenic cyst.

Case Presentation
A 28-month-old girl was referred to our clinic because of a persistent cough, wheeze, and increased work of breathing for the preceding three months. Despite oral antibiotics and high doses of inhaled corticosteroids prescribed by her primary physician, cough and wheeze were persistent. Parents denied any history of witnessed foreign body aspiration, and there were no feeding-related symptoms. e patient was born at term with an uneventful postnatal course. Her history was signi cant for episodes of cough and intermittent wheeze that begun at one year of age; these episodes were usually treated with bronchodilators and inhaled steroids. ere was no history of atopy in the family.
Initial physical examination revealed normal growth parameters, a respiratory rate of 40 breaths/minute, and no retractions. Oxygen saturation ranged from 94 to 95% on room air, and she was afebrile. Lung auscultation revealed decreased air exchange in the left lung; the rest of her physical examination was normal.
A chest X-ray was performed for abnormal breath sounds and showed hyperlucency of the left lung ( Figure 1). A barium swallow study was normal with no apparent external indentation or displacement of the esophagus and no evidence for GERD.
Blood work, including routine hematology and biochemistry tests, was within normal limits. Results of virology PCR for CMV, EBV, and adenovirus were negative. Acidfast bacilli smear, culture, and TB PCR were negative.
On exible bronchoscopy examination of her lower airways, no foreign body was seen, but signi cant external nonpulsatile compression over the left main bronchus was noticed; the rest of the airway anatomy was normal. is nding prompted us to undertake a detailed evaluation. oracic computed tomography (CT) scan and angiogram showed a soft tissue mass in the middle mediastinum, compressing the carina and proximal part of the right and left main bronchi, more pronounced on the left main bronchus ( Figure 2).
is mass was further delineated by magnetic resonance imaging of the thorax with contrast which revealed a lobulated cystic mass lesion ( Figure 3). ese ndings were in favor of the diagnosis of a bronchogenic cyst in the middle mediastinum. erefore, the patient underwent thoracotomy and surgical removal of a cystic mass which was found during surgery to be adjacent to the posterior trachea and left main bronchus. Pathological examination of the mass showed a cystic lesion lined by the ciliated columnar epithelium surrounded by a bromuscular wall containing the cartilage and nests of bronchial submucosal glands, con rming the probable diagnosis of a bronchogenic cyst. ere was no evidence of malignancy. e postoperative course was uneventful. e patient had been free of any respiratory symptoms and signs, including a cough and wheezing in the subsequent follow-up visits.

Discussion
is child presented with a persistent cough and wheeze that were not responding to standard asthma treatment. We considered the causes of wheezing and coughing in children.
erefore, she underwent exible bronchoscopy, CT scan, and magnetic resonance imaging (MRI) of the chest that revealed a bronchogenic cyst in the middle mediastinum. Surgical removal of the mass was successfully performed, and pathologic examination con rmed the diagnosis of the bronchogenic cyst.
Bronchogenic cyst (BC) is a rare congenital pulmonary malformation with a prevalence of 1 : 42,000-1 : 68,000 [3]. BCs constitute 13-15% of the congenital cystic lung diseases and 6% of the mediastinum masses in children [4,5]. Abnormal budding of the ventral foregut leads to the formation of BC anywhere along the respiratory system or esophagus. e location of BC formation can vary depending on the time of their origin [6,7]. Up to 85% are in the mediastinum, and 12% are parenchymal in origin involving primarily lower lobes. However, unusual locations like the neck, pericardium, or abdomen have been reported [1,7,8]. In our patient, BC originated from the trachea in the middle mediastinum.
Ribet et al. reported that BCs were symptomatic in 70.8% of a ected children [6]. e symptoms are usually secondary to either the compressive e ect of the enlarged cyst on the adjacent structures or infection in the cyst. e former is more common in infants and young children presenting as a retraction, cough, and wheeze, while the latter is more common in adults presenting as recurrent pneumonia [4,6,9]. In rare conditions, mediastinal BC can present in the neonatal period with severe respiratory distress and stridor [10]. However, about one-third of BCs are asymptomatic and are found incidentally in adults and some children [2]. In our patient, obstructive symptoms were not present in the neonatal period, but ultimately, she became symptomatic.
Diagnostic studies include chest X-ray, barium swallow, bronchoscopy, and CT scan/MRI of the chest. A chest radiograph is diagnosed in only 77% of cases [11]. Usually, they   Case Reports in Pediatrics reveal well-de ned homogeneous density, tracheal deviation, and a compression e ect-like atelectasis or emphysema. Flexible bronchoscopy may reveal airway compression, and barium swallow may show an indentation [6]. CT scan/MRI of the chest is extremely valuable for accurate diagnosis, de nes the anatomy, and rules out a list of di erentials that include cystic hygroma, lymphangioma, neuroenteric cyst, esophageal duplication cyst, and thymic cyst [1,4,9]. Ultrasonography makes the antenatal diagnosis with a reported accuracy in more than 70% of cases [12]. In our patient, the cyst was not visible on plain lm; it only showed hyperination of the left lung. e bronchoscopy examination drove us toward the diagnosis. e CTscan and the MRI of the chest were highly suggestive of a bronchogenic cyst. In almost all cases, pathological studies are required for a de nitive diagnosis. In our patient, the microscopic ndings revealed a benign bronchogenic cyst. In rare cases, reports of malignant transformation, including pulmonary blastoma, rhabdomyosarcoma, and bronchoalveolar carcinoma, have been found in the resected bronchogenic cyst in adults (0.7%) and children [13]. To prevent further complications and to avoid the possible risk of malignant changes, complete surgical removal of the BC is strongly recommended even in asymptomatic individuals [4,6].
In conclusion, although a chronic cough and wheeze are common symptoms of asthma in children when these symptoms do not respond to conventional treatment strategies, this should prompt the clinician to seek further investigations looking for other causes of persistent "asthma-like symptoms." Bronchogenic cysts are an uncommon developmental anomaly of the tracheobronchial tree, which may cause airway compression and mimic asthma. Pediatricians should consider bronchogenic cyst as an important asthma masquerader, particularly in young children who have persistent symptoms and inadequate response to asthma therapy. Surgical resection remains the treatment of choice in all cases to con rm the diagnosis and to prevent unpredicted complications.

Ethical Approval
Ethical approval and consent to participate were obtained from the Medical Research Center at Hamad General Hospital with Reference number 16329/16.

Consent
Written informed consent to participate was obtained from the parents.

Conflicts of Interest
e authors declare that they do not have nancial or non nancial con icts of interest to disclose.

BC:
Bronchogenic cyst GERD: Gastroesophageal re ux PCR: Polymerase chain reaction CMV: Cytomegalovirus EBV: Epstein-Barr virus TB: Tuberculosis Chest CT scan: Chest computed tomography scan Chest MRI: Magnetic resonance imaging of the chest. Case Reports in Pediatrics 3