To the Editor: Pneumomediastinum (PM) is a rare condition in children. Many conditions can trigger this [1]. Here we describe an adolescent boy with PM as the presenting manifestation of acute asthma exacerbation.

A 12-y-old boy presented with cough (25 d), chest pain (4 d), facial puffiness, and breathing difficulty (3 d). He had a history of breathing difficulty 3 y ago, but he was not on medication. There was no family history of atopy. He was tachypneic, and oxygen saturation was 90% in room air. There was facial puffiness with palpable crepitus extending to bilateral neck and chest (Supplementary Fig. S1a). Diffuse biphasic polyphonic wheezes were heard. Hamman’s sign was positive. A clinical diagnosis of asthma exacerbation with subcutaneous emphysema (SCE) was kept with a plan to exclude pertussis, foreign bodies and look for evidence of trauma. He was started on therapy for asthma exacerbation. Chest X-ray showed PM and SCE (Supplementary Fig. S1b). The findings were similar in CECT chest, and there was no evidence of trauma or foreign body (Supplementary Fig. S1c). Polymerase chain reaction (PCR) for pertussis was negative. Due to relative contraindications, pulmonary function test was not performed. There was marked clinical improvement within 48 h. He was discharged on a daily inhaled corticosteroid. At one month of follow-up, his asthma symptoms were well-controlled.

The reported incidence of PM in children is 0.3 to 5% [2]. It can be spontaneous pneumomediastinum (SPM) or traumatic pneumomediastinum. The triggers for SPM in children include underlying respiratory conditions with intense cough, gastrointestinal disorders with excessive vomiting, strenuous exercise, seizures, and diabetic ketoacidosis [3]. The diagnosis is mainly clinical and can be confirmed by chest imaging. It is usually a self-limiting condition, and treatment is mainly supportive for uncomplicated cases. Any underlying lung disease had to be treated accordingly [4].

In conclusion, though PM and SCE are rare in children, they could be the initial manifestation of asthma exacerbation.