A mediastinal mass may be asymptomatic even when it reaches a significant size. It may be discovered during routine radiological testing for the disease causing the mass or just incidentally [1].

When the mass reaches a critical size within the restricted mediastinal space, it can cause signs and symptoms related primarily to the cardiac or pulmonary system. This can include diminished venous return via the superior vena cava (SVC) leading to fullness of the neck veins and in extreme cases cardiac dysfunction from direct compression. Respiratory symptoms could range from dyspnea, progressive orthopnea, voice changes (nerve palsy), and in late stages stridor.

Deviation of the trachea. This could include:

Narrowing and invasion of the lumen of the trachea and/or major bronchus:

Lack of symptoms should not be considered as reassuring. This is especially true with superior or anterior mediastinal masses. With spontaneous ventilation, the mechanics of thoracic cage cause a distracting force on the larger airways by maintaining the intrapleural pressure gradient, helping to maintain the patency of the lumen. The loss of bronchial tone due to general anesthesia can also decrease lumen size. Thirdly, the distension of the major airways will be diminished with smaller ventilatory volumes [2]. The loss of normal spontaneous ventilation during general anesthesia can thus precipitate intrathoracic airway obstruction in such cases with catastrophic results [3].