An abnormal chest radiograph

BMJ 2014;349:g6592 doi: 10.1136/bmj.g6592 (Published 13 November 2014)

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An abnormal chest radiograph Avinash Aujayeb specialist respiratory registrar, Mark Weatherhead consultant in respiratory medicine Department of Respiratory Medicine, Wansbeck General Hospital, Ashington NE63 9JJ, UK

A 55 year old man presented to the emergency department with syncope after laughing. His full examination was documented as normal, and no abnormalities were seen in his electrocardiograph or routine blood tests. Blood pressure when lying and standing was normal. However, his chest radiograph and the results of computed tomography were abnormal (figs 1 and 2).

Fig 1 Chest radiograph

Fig 2 Computed tomogram of the chest

He had never smoked, had no occupational dust exposure, and had no pets such as birds or cats. He had noticed some exertional dyspnoea and a mild cough over the past few months, but no haemoptysis. In addition, he had no weight loss or night sweats.

Correspondence to: A Aujayeb [email protected] For personal use only: See rights and reprints http://www.bmj.com/permissions

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Questions 1. What does the chest radiograph show? 2. What does the computed tomogram show? 3. What are the differential diagnoses? 4. What further investigations and management would you plan?

of adjacent structures. Laughing and compression of the superior vena cava by the mass probably produced a great enough reduction in cardiac output to cause syncope. Laugh syncope has been described in the literature—laughter on its own causes repetitive forced expirations and increased intrathoracic pressure, which reduces venous return, cardiac output, and thus cerebral perfusion.1

Answers

1. What does the chest radiograph show? Short answer

There is marked deviation of the trachea to the right, with a homogeneous opacity in the upper mediastinum.

Long answer

The radiograph shows marked deviation of the trachea to the right, with a homogeneous opacity in the upper mediastinum (fig 3). The trachea extends from about 2 cm below the vocal cords to the carina, where the bifurcation into right and left main bronchi occurs. The radiographic appearance of the tracheal air column is vital to the overall interpretation of a chest radiograph. Tracheal deviation is a clinical sign that suggests an imbalance in intrathoracic pressure. Conventional teaching suggests that deviation away from the side of the lesion is secondary to causes such as tension pneumothorax or a large pleural effusion. Deviation towards the side of the lesion suggests volume loss as a result of fibrosis, a tumour, or surgery (lobectomy or pneumonectomy). However, direct pressure from enlarging organs can also cause deviation and compression.

Fig 4 Contrast enhanced computed tomogram showing an anterior mediastinal mass arising from the thyroid (long arrow), causing tracheal deviation and narrowing (short arrow)

3. What are the differential diagnoses? Short answer Teratoma, lymphoma, goitre, and thymoma.

Long answer

The mediastinum is bordered by the diaphragm, the thoracic inlet cavity, the sternum, the vertebral spine, and the pleural spaces. The space can be divided into anterior, middle, and posterior compartments. The anterior compartment is bordered by the sternum and the ventral cardiac surface. The middle compartment goes from the anterior compartment to the anterior surface of the spine, and the posterior compartment runs parallel to the vertebral column from the fourth to the 12th vertebra and is closed by the pleura, diaphragm, and pericardium. The table⇓ summarises the potential differential diagnoses according to the anatomical position of the mass. There is an “aide memoire” that, although not completely correct, is widely taught and can help when trying to remember the potential causes. It is the “4Ts”—teratoma, terrible lymphoma, thyroid masses, and thymoma. Fig 3 Chest radiograph showing an upper mediastinal mass (arrow) and marked deviation of the trachea to the right (arrowheads)

2. What does the computed tomogram show? Short answer

It shows a large mass in the anterior mediastinum that seems to arise from the thyroid.

Long answer

The computed tomogram shows a large mass in the anterior mediastinum that seems to arise from the thyroid (fig 4). Mediastinal masses are usually incidental diagnoses. However, some patients present with symptoms related to compression For personal use only: See rights and reprints http://www.bmj.com/permissions

4. What further investigations and management would you plan? Short answer

Thyroid function tests and flow volume loops. Referral to the cardiothoracic team.

Long answer

If serum thyrotrophin is abnormal, refer the patient for expert advice from an endocrinologist for pharmacological treatment. However, most patients are euthyroid. Spirometry is useful for assessing the need for surgery in a patient without obstructive symptoms. A characteristic pattern of upper airway obstruction can be shown as flattening of the inspiratory and expiratory loops. Referral to the cardiothoracic team is often necessary.



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Patient outcome The patient was immediately referred to the cardiothoracic team.

His age makes a teratoma unlikely, and the absence of adenopathy and type B symptoms anywhere else goes against the mass being a lymphoma. The computed tomogram confirmed that it was a thyroid mass and that the serum thyrotrophin was normal. Substernal goitres are located in the anterior mediastinum in about 90% of cases. Exertional dyspnoea tends to occur when the trachea narrows to less than 8 mm. Given his symptoms, he was listed for surgery and went on to have an uncomplicated left hemithyroidectomy by a cervical approach. A sternotomy was not performed. He was discharged with a hoarse voice, and histological examination showed multinodular thyroid tissue and no malignancy.

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He currently remains well and is under follow-up. Competing interests: We have read and understood BMJ policy on declaration of interests and declare the following interests: none. Provenance and peer review: Not commissioned; externally peer reviewed. Patient consent obtained. 1

Nishida K, Hirota SK, Tokeshi J. Laugh syncope as a rare sub-type of the situational syncopes: a case report. J Med Case Rep 2008;2:197.

Cite this as: BMJ 2014;349:g6592 © BMJ Publishing Group Ltd 2014



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Table Table 1| Differential diagnosis of a mediastinal mass according to the anatomical position Anterior compartment

Middle compartment Posterior compartment

Thymoma or carcinoma

Bronchogenic cyst

Thoracic spine lesions

Lymphoma

Tracheal tumour

Lymphadenopathy

Germ cell tumour

Vascular aneurysms

Neuroenteric cyst

Thyroid mass

Aortic dissection

Neurogenic tumours

Foramen of Morgagni hernia Pericardial cyst

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