Traumatic pseudocyst of the lung following blunt trauma to the chest
- 1 Radiology, KEM Hospital and Seth GS Medical College, Mumbai, Maharashtra, India
- 2 Radiodiagnosis, Seth GS Medical College and KEM Hospital, Mumbai, India
- Correspondence to Dr Akshay Nanaji Desale; akshaydesale@gmail.com
Abstract
Traumatic pseudocysts of the lung are a rare complication following blunt trauma to the chest. Differentiating them from other cystic lesions of the lung is important. Traumatic pseudocysts usually occur in children and young adults who present with haemoptysis and persistent pain. History of trauma and radiological evaluation with a chest radiograph and a CT scan help in making the diagnosis. Follow-up chest radiographs showing resolution of the pseudocyst can confirm thediagnostic confirmation. This is a report of one such patient, a young man who improved after conservative treatment, with spontaneous radiological resolution of the pseudocyst.
Background
Post-traumatic pulmonary pseudocyst is a rare complication following blunt trauma to the chest,1 and on rare instance following penetrating trauma to the chest.2 It is a self-limiting condition and resolves with time without any medical or surgical treatment in most of the patients. It is a lesser known entity and can mimic other cystic lesions of the lung.3 Knowledge of this entity will help in proper management.
Case presentation
We report a case of a man in his 20s who sustained trauma to the right side of the chest due to fall from a tree. He presented to the hospital 10 days later with complaints of a single episode of haemoptysis and persistent pain on the right side of the chest that increased on deep inspiration. The patient came from a remote rural area without any written documentation of the treatment he had received at the facility. Hence we were solely reliant on the patient’s history. The patient was healthy prior to the trauma. On clinical examination there were abrasions on the right side of the chest and crepitus on palpation, with positive chest compression test.
Admission chest radiograph (figure 1) showed a well-defined, thin-walled cavity with an air-fluid level in the right lower zone. A poorly defined soft tissue shadow was seen superior to this cavity. Scattered areas of airspace opacification were seen in the right upper zone and mid-zone. There was pneumomediastinum with subcutaneous emphysema.
Frontal chest radiograph shows a well-defined, thin-walled cavity with air-fluid level in the right lower zone (thick white arrow). Patchy areas of airspace opacification are seen surrounding the cavity suggestive of contusions. Pneumomediastinum is seen (thin white arrows).
A CT scan (figure 2A,B) was done following the chest radiograph. This showed a thin-walled cavity in the anterior basal segment of the right lower lobe abutting the horizontal fissure. The cavity showed hyperdense content, indicating blood. There were few thin-walled cavities in the lateral segment of the right middle lobe with surrounding ground glass opacification (figure 2C). There were few patchy densities with surrounding ground glass opacification in the posterior segment of the right upper lobe and the posterior basal segment of the right lower lobe. There was pneumomediastinum. The subcutaneous emphysema was extending into the interfascial planes of the neck. There were no rib fractures (figure 2D).
Axial sections of the lung on HRCT (High resolution comuted tomography) and soft tissue window. (A) An oval-shaped pseudocyst on the right lower lobe with air-fluid level within (thick white arrow) and two circular smaller pseudocysts in the anterior segment of the right upper lobe (thin white arrows). (B) An oval-shaped pseudocyst with blood within it HU 60 (Hounsfield unit) (thin blue arrow). (C) Patchy opacities with surrounding ground glass opacification on the right lower lobe suggestive of contusions (thick white arrow). (D) Pneumomediastinum with subcutaneous emphysema (thin black arrows).
Outcome and follow-up
On follow-up at the end of 3 months, the chest radiograph (figure 3) showed diminution in the size of the cystic lesions, with resolution of the contusions and pneumomediastinum.
Frontal radiograph of the chest done after 3 months following trauma shows near-complete resolution in the size of the cystic lesion (thick white arrow), with resolution of the contusions and pneumomediastinum.
Discussion
A traumatic pseudocyst of the lung is a rare complication following blunt trauma to the chest. Pseudocyst is a thin-walled cavity which is not lined by an epithelium, hence termed pseudocyst (figure 4).3
Line diagram of the pseudocyst. Created by Akshay Nanaji Desale.
Traumatic pseudocyst of the lung develops following blunt trauma to the chest, but few cases have been found after penetrating injury to the chest.2 The explanation that has been proposed is the rapid compression and decompression of the chest following trauma, especially against a closed glottis which will lead to lung laceration and formation of a cyst filled with air and blood. Such a patient may present with haemoptysis. In cases where no rib fractures are detected, the source of haemoptysis is from rupture of the pseudocyst.3 Compressive force of a high-velocity impact with low displacement leads to the formation of peripheral pseudocyst, while a low-velocity impact with high displacement leads to central pseudocyst formation.3
A traumatic pseudocyst of the lung can develop in any age group but has been found more frequently in children and young men due to the greater elasticity of their chest wall and the greater incidence of trauma in young men. Elasticity allows easy transmission of the force.4
On chest radiographs, a traumatic pulmonary pseudocyst appears as a well-defined cystic lesion or a thin-walled cavity with air-fluid level. A pseudocyst may not be visible on the chest radiograph obtained on the same day of trauma as it may get obscured by lung contusions.5
Pneumatocele, tuberculous cavity, ruptured hydatid cyst, cavitating bronchial cancer, lung abscess and bronchogenic cysts are all possible differential diagnoses of traumatic pseudocyst of the lung. Any confusion is usually differentiated by a history of trauma, preliminary CT, sequential changes on serial chest radiograph and presence of contusions. Other aetiologies must be examined if the cavitatory lesion does not improve with time.2 6 CT scan will show thin-walled single or multiple cysts with or without air-fluid level (blood) and surrounding contusions in traumatic pseudocyst of the lung. However, tuberculous cavity, cavitating bronchial cancer and abscess will show thick irregular enhancing wall without surrounding contusions and rib fractures. Ruptured hydatid cyst shows undulating membranes within a collapsed cyst on CT and can show daughter cysts within. Intrapulmonary bronchogenic cysts are rare and prior imaging will help in differentiating them from pseudocysts.
A CT scan is necessary in the preliminary stage as it helps in the early identification of cystic lesions when they are smaller even though they are surrounded by the contusions. CT helps in the evaluation of the severity of the injuries in the lung and in deciding the management of the disease. Follow-up examinations can be with chest radiographs alone. Other associated findings such as pneumomediastinum, pneumothorax and rib fractures point to a traumatic aetiology of the cyst. It is essential to review any recent relevant imaging studies to know the chronology of the lesion.
Traumatic pseudocysts of the lung are often of varying sizes at presentation and multiple lesions are frequently found. Usually, a contralateral lung involvement is seen due to the contrecoup nature of the injury. There is no lobar predominance; however, the lower lobes are more predominantly involved, with relative sparing of the apices.5 7
The course of the traumatic pseudocyst of the lung is mostly uneventful and resolves on follow-up chest radiographs. Accurate diagnosis aids in avoiding percutaneous drainage or surgery in the event of the cyst being uncomplicated.
Complications associated with traumatic pseudocysts such as rupture into the pleura causing pneumothorax, bleeding, secondary infection or causing compression of the airway are rare; in all such cases, medical management or percutaneous drainage is necessary.8 If there is progressive increase in pseudocysts and significant respiratory distress owing to lung collapse, surgical intervention such as lobectomy may be required.9
Learning points
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The course of traumatic pseudocyst of the lung is mostly uneventful and resolves on follow-up chest radiographs in majority of the cases.
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The combination of CT, clinical history and previous imaging aids in differentiating pulmonary pseudocysts from other cavitary lesions in the lungs.
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Follow-up imaging aids in the identification of complications and thus timely management of the same.
Ethics statements
Patient consent for publication
Acknowledgments
The authors express their gratitude to the Department of Radiology of Seth GS Medical College and KEM Hospital, Mumbai, for providing the required platform to complete this case report. They are thankful to the patient without whom it would not have been possible to complete the report. They also thank their colleagues for their extended support in preparing this manuscript. The authors would like to thank Dr Ravi Ramakantan for his invaluable guidance.
Footnotes
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Contributors PVB was involved in the first and critical revisions of data and final approval. AND was involved in writing the first draft of the manuscript. CDR was involved in the interpretation of radiological images and obtaining follow-up. MGN drafted the article.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
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Competing interests None declared.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.
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