CASE 11239 Published on 13.12.2013

Tension bulla

Section

Chest imaging

Case Type

Clinical Cases

Authors

Vesela Zhekova, Max Scheffler

Geneva University Hospital,
Department of Radiology,
Rue Gabrielle-Perret-Gentil 4,
1205 Geneva, Switzerland
Patient

48 years, male

Categories
Area of Interest Thorax, Lung ; Imaging Technique Conventional radiography, CT, CT-High Resolution
Clinical History
A 48-year-old male patient was admitted to the emergency department presenting acute dyspnoea without chest pain. Clinical examination revealed decreased left basal breath sounds. The patient's saturation was 97% on oxygen therapy. His past medical history was noteworthy for tobacco use and chronic obstructive pulmonary disease (COPD) with bullous emphysema.
Imaging Findings
The admission chest radiograph (Fig. 1) revealed an increased lucency of the left lung, particularly pronounced in the left upper lung field where no vasculature could be identified, left-sided paracardiac atelectatic bands, and a right medistinal shift, simulating tension pneumothorax. However, no visceral pleural line was seen and a CT was requested, to rule out bullous rupture with loculated pneumothorax. On this CT there was no evidence of pneumothorax (Fig. 2a, b). However, in comparison with a previous CT study (Fig. 3a, b), a giant left apical emphysematous bulla had increased in size, occupying the entire left upper lobe with increased mass effect responsible for lingular compressive atelectasis and a progressed contralateral mediastinal shift.
Discussion
A bulla is defined as an airspace greater than 1 cm in diameter demarcated by a thin wall of parenchymal remnants [1]. It is called a giant bulla when lit involves more than one third of a hemithorax, typically located in an upper lobe. A tension bulla is a giant bulla that increases in size by a check-valve mechanism of air trapping and has a growing mass effect on the underlying lung parenchyma as well as the mediastinum. Bullae are associated with tobacco-related emphysema, other COPD findings like asthma and bronchiectasis, as well as collagen-vascular diseases [1].
Clinical presentation of tension bulla usually includes acute dyspnoea and chest pain but is nonspecific. On standard radiographs giant bulla, tension bulla, tension pneumothorax, and atypical (clustered) pneumothorax can be difficult to distinguish, making CT necessary to establish the accurate diagnosis [2, 3].
On chest radiographs, bullae appear as well delineated areas of avascularity. A bulla has a thin curvilinear fibrous wall that may not be perceptible on radiographs but only on CT. Surrounding lung parenchyma typically collapses if the bulla is under tension, whereas a nonfunctional giant bulla exerts less mass effect. A pneumothorax on the other hand represents a pleural collection of air, surrounded by visceral pleura on one side, and parietal pleura on the other. If there is an increasing accumulation of air in the pleural space, due to limited egress, the pneumothorax gets under tension with similar haemodynamic consequences as a tension bulla. An atypical pneumothorax may occur in a setting of pleural adhesions. In this case, the lung collapses toward the hilum, but remains partially attached to the chest wall [4]. A single non-enhanced CT series acquired during inspiration breath hold is usually sufficient to establish the diagnosis of pneumothorax.
Bullectomy is the treatment of choice for tension bulla, whereas pleural drainage is indicated for tension pneumothorax [4]. Non-complicated giant bullae may be treated conservatively, with bronchoscopic intervention with deployment of bronchial valves, or lung volume reduction coils. Surgical lung reduction is less often indicated. The natural evolution of bullae is slow progression although there are few cases reported in the literature of spontaneous resolution of giant bullae [5].
In conclusion, a tension bulla may mimic an atypical pneumothorax, a tension pneumothorax, or a non-complicated giant bulla. Its correct diagnosis has an impact on treatment which differs from that of the other three entities.
Differential Diagnosis List
Tension bulla
Tension pneumothorax
Atypical pneumothorax
Giant bulla
Final Diagnosis
Tension bulla
Case information
URL: https://www.eurorad.org/case/11239
DOI: 10.1594/EURORAD/CASE.11239
ISSN: 1563-4086