Mediastinal cyst: a rare cause of acute respiratory distress in an adult

Description

A 57-year-old woman attended the accident and emergency department in acute respiratory distress with a background of a longstanding retrosternal ‘ache’. She had previously presented to the accident and emergency department with a similar history, which responded to nebulised salbutamol, and had therefore previously been given a diagnosis of asthma. On this occasion, she did not respond to asthma treatment and required ventilatory support in the intensive care unit.

A chest radiograph on admission showed an abnormal mediastinal contour that, in retrospect, had been present on previous chest radiographs. She subsequently underwent CT and MRI of her chest. The MRI showed a 9.4 cm × 7.3 cm × 10 cm central mediastinal cyst compressing both main bronchi (figure 1). She underwent bronchoscopic drainage of the cyst acutely, which was clinically and bronchoscopically successful, and definitive surgical excision via median sternotomy 1 month later. Histology confirmed a foregut duplication cyst. A follow-up CT at 1 year after excision showed no recurrence.

Figure 1.

Sagittal MRI showing a large, multiloculated mediastinal cyst.

Foregut duplication cysts are seen in children but rarely in adults.^{1 2} Complications include respiratory distress, haemoptysis and acute rupture.³ Surgical excision offers definitive management as bronchoscopic drainage, though successful at managing acute airway obstruction by the cyst, leaves the cyst able to refill.

Learning points.

• Mediastinal cysts are a rare, but important, cause of acute respiratory distress.

• If a patient fails to respond to therapy based on a previous diagnosis or previous imaging, it is important to reconsider the initial diagnosis and review all previous investigations to consider alternative diagnoses.