Life-Threatening Mediastinal Shift due to a Giant Bronchogenic Cyst

Introduction

Bronchogenic cysts (BCs) are congenital abnormalities originating during the development of the primitive foregut and occurring with a prevalence of 1 : 42,000 to 1 : 68,000 (Coselli MP et al., Ann Thorac Surg 1987; 44: 491–494). BCs account for 40–50% of all primary mediastinal masses in children and are clinically asymptomatic in most cases (Ribet ME et al., J Thorac Cardiovasc Surg 1995; 109: 1003–1010). Nevertheless, life-threatening complications due to compression, infection, hemorrhage, and rupture are described in the literature (Jaggers J et al., Semin Thorac Cardiovasc Surg 2004; 16: 201–208).

Case Presentation

We present the case of a 6-year-old boy (117 cm, 20 kg) without noteworthy medical history until 6 months before admission. The patient presented with dry cough and exertional dyspnea. Physical examination revealed an inspiratory stridor, a reduced breathing sound on the left side with a concomitant flail chest and intercostal confiscations. A subsequently performed X-ray demonstrated consecutive complete atelectasis of the left lung and advanced mediastinal shift ([Fig. 1a]). A computed tomography (CT) scan depicted a mass of 38 x 32 mm in the posterior mediastinum ([Fig. 2a, b, c]). The most likely differential diagnosis were a bronchogenic cyst (BC) or a cystic lymphangioma. Due to acute respiratory deterioration, decreasing peripheral oxygenation (SpO₂ 90% despite insufflation of 12 l O₂ via inhalation mask) and worsening arterial blood gas analysis during anesthetic induction, rescue surgery was performed. The standard surgical approach of video-assisted thoracoscopic surgery (VATS) was evaluated too hazardous in this specific case without adequate access to the femoral vessels in case of extracorporeal membrane oxygenation (ECMO) necessity. A median sternotomy was performed for an adequate exposure of the mass without compromising the remaining pulmonary tissue. An ECMO was kept on standby in case of further respiratory or hemodynamic deterioration. Following sternotomy, visualization of the cyst was feasible using retraction sutures with considerable force on the pericardium pulling the heart back to midline. A window was prepared between the ascending aorta and the superior vena cava to access the trachea. The BC was identified and excised in toto. Simultaneous bronchoscopy revealed immediate relief of the tracheal and bronchial obstructions and ventilation pressures normalized. The patient was extubated in the operating room utilizing an ultra-fast-track protocol. The course in intensive care was uneventful and the patient was transferred to the normal ward and mobilized on the first postoperative day. At day 5 a fever and a recurrent cough appeared as manifestations of an infection of the respiratory tract. A pulmonary reperfusion syndrome could have led to these symptoms, but neither characteristic pulmonary infiltrates, pleural effusions nor lung edema were seen. After treatment with antibiotics, the patient was discharged six days later without symptoms and with a near normal chest X-ray ([Fig. 1b]). Histopathology ([Fig. 3a, b]) showed typical characteristics of a BC. On last follow-up visit (16 months after operation), the patient was asymptomatic without any medical limitation and normal pulmonary function testing. CT showed a normal finding without any signs of residua or recurrence of the cyst.

Fig. 1 Chest X-ray a Preoperative chest X-ray: Anteroposterior view shows complete atelectasis of the left lung and advanced mediastinal shift to the left side. A more transparent area adjacent to the left-sided atelectasis is delineated with a dotted line. b Postoperative chest X-ray: Anteroposterior view shows a completely evolved left lung and a completely reversed mediastinal shift three days after the operation.

Fig. 2 CT scan of the thorax a Coronal view shows a giant cystic structure (38 x 32 mm) in the posterior mediastinum with severe compression of the left main bronchus. b Transversal view shows compression of the trachea and atelectasis of the left lung with impressive mediastinal shift to the left as well as hyperinflation of the right lung. c Anatomic relations of the BC are depicted in the sagittal plane. BC= bronchogenic cyst

Fig. 3 Hematoxylin and Eosin staining (20x magnification) of the bronchogenic cyst a Typical manifestation of ciliated respiratory tract epithelium (*) on the inside of the cyst with different wall structures. The epithelium consists of a small basement membrane (BM), smooth muscle tissue (SM) and cartilage (C). b Epithelium with mucus glands (→) is shown.

Comment

Bronchogenic cysts are usually diagnosed accidentally on chest X-ray indicated for other unrelated reasons (Adzick NS et al., Pediatric Surgery 2012; 825–835). Characteristically being of benign origin, they can however also lead to perilous complications, including compression of surrounding structures, infection, hemorrhage and rupture (Jaggers J et al., Semin Thorac Cardiovasc Surg 2004; 16: 201–208). Due to the risk of malignant transformation, possibly leading to complications in adulthood, all lesions are usually completely surgically removed, even in asymptomatic patients (Fievet L et al., Ann Thorac Surg 2012; 94: 1695–1699). Treatment of BCs in children is performed the same way as in adults, though the anatomical proportions in pediatric patients are much smaller. The surgical access site and mode have to be chosen carefully with respect to the location and the dimension of the BC (Takeda S et al., Chest 2003; 124: 125–132). The treatment of choice is complete surgical excision, preferably realized by VATS. With the development of smaller surgical instruments for pediatric use, VATS is principally the gold standard even in more difficult situations (Adams S et al., J Pediatr Surg 2017; 52: 247–251; Jung HS et al., Interact Cardiovasc Thorac Surg 2014; 19: 824–829; Macchini F et al., J Laparoendosc Adv Surg Tech A 2020). However, median sternotomy can be a useful bail-out strategy for the very few cases with an unpredictable operative and postsurgical course, especially in those with no appropriate vascular access to the femoral vessels for central cannulation in case of ECMO necessity. In conclusion, we recommend early surgery for BCs via VATS once detected to avoid unnecessary aggravation of the patient’s condition as presented above. Referral to an experienced center with a trained interdisciplinary team is advised to find the best individual surgical approach for each patient.

Publikationsverlauf

Artikel online veröffentlicht:
14. Mai 2020