Case report of a child with spontaneous pneumomediastinum and subcutaneous emphysema

Abstract

Hamman’s syndrome is a rare clinical entity that presents with spontaneous pneumomediastinum and subcutaneous emphysema. It is most commonly diagnosed in young men and pregnant women, and is rare in children. We report the case of a female toddler who presented to an emergency department with fever, cough and shortness of breath. Imaging studies revealed subcutaneous emphysema and pneumomediastinum. The patient was diagnosed with Hamman’s syndrome after ruling out other possibilities. We discuss the underlying mechanisms of the disease, the diagnostic criteria and the treatment options. The purpose of this case report is to improve clinicians’ awareness of the existence of this rare clinical entity in paediatric patients.

Introduction

Hamman’s syndrome, also known as Macklin’s syndrome, is a rare condition characterised by spontaneous pneumomediastinum and subcutaneous emphysema. Although it is generally a self-limiting illness that can be managed conservatively, it can also be fatal if severe and left untreated. Hamman’s syndrome is most commonly diagnosed in young men and pregnant women, and is rare in children. ¹ The aetiology involves several factors, such as vigorous Valsalva manoeuvre during pregnancy, self-induced vomiting, severe coughing, recreational drug inhalation, and extreme physical exertion. ² The rupture of marginal alveoli into the perivascular tissue planes causes air to be trapped in the mediastinum. Chest X-ray is an effective diagnostic tool and can be used to determine the prognosis of the disease. However, the ruling out of other more common causes of pneumothorax is important to establish the diagnosis. ³

Case report

A 17-month-old girl was admitted to the emergency department of the hospital with fever, malaise, dry cough and progressive shortness of breath of 1 week’s duration. On presentation, her vital signs were as follows: heart rate 110 beats per minute, respiratory rate 52 breaths per minute, temperature 39.0°C, blood pressure 80/60 mmHg and oxygen saturation 98% while being administered oxygen via a nasal cannula. Arterial blood gas measurements revealed mild metabolic acidosis (pH 7.33, [ ${\text{HCO}}_3^{-}$ ] 16 mmol/L and pCO₂ 6.27 kPa). Physical examination revealed tachypnoea with subcostal retractions. Bilateral subcutaneous emphysema was palpable between the neck and the diaphragmatic region and involved both the anterior and posterior sides of the chest wall. Auscultation revealed low air entry bilaterally, with wheezes and crepitation that were most noticeable on the left side. There was no history of trauma or surgical intervention.

Subcutaneous emphysema and pneumomediastinum were apparent on a chest radiograph that was obtained at the time of admission (Figure 1). High-resolution contrast chest computed tomography was also performed to confirm the X-ray findings and to exclude other potential causes of pneumomediastinum. This showed pan-lobar emphysema and pneumomediastinum associated with the left lung and a small area of pneumothorax ipsilaterally. A large area of consolidation was also apparent in the lower lobe of the left lung. In addition, a few patches of emphysema were present in the middle and lower lobes of the right lung, and diffuse subcutaneous and soft tissue emphysema was identified in the neck, chest and abdomen. The imaged portions of the great vessels, heart, trachea, oesophagus and upper abdomen were normal. There was no pericardial effusion, the heart size was normal, the aorta and great vessels were of normal calibre, and there were no signs of embolism in the central pulmonary arteries. The trachea and mainstem bronchi were patent, and the course of the oesophagus and its diameter were normal. Finally, the osseous structures of the chest were normal, and there was no visible oesophageal, tracheal or laryngeal perforation or fistula. After ruling out all other possibilities, the patient was diagnosed with Hamman’s syndrome. She was monitored closely for 1 day, before being sent home, because her condition remained stable. Her emphysema had fully resolved by the time she was re-examined 4 days later, and a chest X-ray obtained at this time was normal.

Figure 1.

Chest X-ray of the patient obtained at the time of admission, showing extensive subcutaneous emphysema and pneumomediastinum.

Discussion

Hamman’s syndrome, which is characterised by the release of air into the mediastinum and subcutaneous tissues and pneumothorax was first described by Louis Hamman in 1939. ⁴ It is a rare condition that can be fatal if left untreated. This syndrome can be caused by a variety of factors that result in an increase in intrathoracic pressure, leading to alveolar rupture and the release of air, which travels along its pressure gradient through vascular planes to the pulmonary hila and into the mediastinum (the Macklin effect).^5,6 The majority of cases have been reported in women during their second stage of labour ⁷ and in young men who are prescribed inhaled medication. ⁶ It can occur owing to a decrease in interstitial pressure secondary to violent coughing, vomiting, vigorous Valsalva manoeuvre during defecation, vigorous physical exercise, the inhalation of recreational drugs and even during the blowing up of party balloons. ² It can also be a feature of conditions including asthma, chronic obstructive pulmonary disease and respiratory distress syndrome in neonates. ⁸ However, it can also develop without any identified precipitating event, as in the present case.

Pneumomediastinum owing to Boerhaave syndrome should be excluded before a diagnosis of Hamman’s syndrome is made, because this can also result in the accumulation of free air in the mediastinum. Hamman’s syndrome is usually a self-limiting condition with a favourable prognosis and can be managed conservatively. However, a substantial build-up of air in the mediastinum can cause an increase in pressure on the thoracic great arteries and trachea, which may ultimately be fatal. Severe pneumothorax is also a possible complication, and this can cause pleuritic chest discomfort, dyspnoea, reduced breath sounds, chest expansion, tachypnoea, cyanosis and tachycardia on the affected side. ⁷ “Hamman’s sign”, a crunching sound that is synchronised with the heartbeat, may also be present. ⁵

Here, we have presented a rare case of Hamman’s syndrome in a 17-month-old girl. The patient’s family provided their consent for the treatment of patient and informed consent was received from the parents to publish the present case report. All the details of the patient have been de-identified in the manuscript. The reporting of this study conforms to the CARE guidelines. ⁹

Conclusion

Hamman’s syndrome is a rare condition in children. However, prompt recognition and appropriate management are crucial to prevent complications, and therefore it should be considered on the list of differential diagnoses for pneumomediastinum and emphysema in this patient group. Although most cases are benign, severe pneumothorax and fatal complications can occur.

This is a syndrome that is not frequently recognised by physicians; therefore, the present case study has been published to raise awareness of this condition. In this way, a more rapid diagnosis might be made, with benefits to the patient and lower treatment costs.

Supplemental Material

sj-pdf-1-imr-10.1177_03000605231200269 - Supplemental material for Case report of a child with spontaneous pneumomediastinum and subcutaneous emphysema

Supplemental material, sj-pdf-1-imr-10.1177_03000605231200269 for Case report of a child with spontaneous pneumomediastinum and subcutaneous emphysema by Murtaza Ali Gowa, Syed Muhammad Aqeel Abidi, Bakhtawer Chandio and Hira Nawaz in Journal of International Medical Research