The use of specific antibodies in inflammatory myopathies has improved the characterization of this disease, identifying different clinical phenotypes. Patients with dermatomyositis (DM) and anti-MDA5 antibodies display typical skin symptoms, lesser muscular involvement, and a prevalence of interstitial lung disease (ILD) of up to 91%. Beyond ILD, spontaneous pneumomediastinum (SN) has been identified as a rare but potentially fatal pulmonary manifestation. Two cases of this complication in patients with anti-MDA5 DM are reported.

Spontaneous pneumomediastinum is the presence of free air in the mediastinum that does not occur from direct thoracic or esophageal trauma. It is a very rare condition usually related to patients with asthma, respiratory infections, or foreign body aspiration. Only a few cases are reported to be associated with severe reflux events.
We present the case of a 10-year-old female with spontaneous pneumomediastinum extending to the neck secondary to severe and persistent hiccups, with no history of asthma, trauma, surgery, acute infection, foreign body aspiration, and intense exercise with Vasalva.
The irritation of the distal third of the esophagus produced severe and persistent episodes of hiccups that increased the intrathoracic pressure, which in turn triggered the pneumomediastinum by Macklin effect. The diagnosis is made with imaging studies. The treatment is conservative with resolution of the clinical picture between five and seven days after hospitalization.
El neumomediastino espontáneo es la presencia de aire libre en el mediastino que no ocurre por un trauma torácico o esofágico directo. Es un padecimiento muy raro, que usualmente ocurre en pacientes con asma, infecciones respiratorias o aspiración de cuerpo extraño. Se reportan pocos casos asociados a eventos de singultos por reflujo grave.
Se presenta el caso de una paciente de 10 años con neumomediastino espontáneo y extensión al cuello secundario a un episodio grave y persistente de hipo sin antecedentes de asma, trauma, cirugía, infección aguda, aspiración de cuerpo extraño ni ejercicio intenso con Vasalva.
La irritación del tercio distal del esófago produjo los episodios graves y persistentes de hipo que incrementaron la presión intratorácica, que a su vez por efecto Macklin, desencadenó el neumomediastino. El diagnóstico se realiza con estudios de imagen. El tratamiento es conservador, con resolución del cuadro clínico entre 5 y 7 días después de la hospitalización.

OBJECTIVE: To describe the radiologic findings of extrapulmonary air in the chest and to review atypical and unusual causes of extrapulmonary air, emphasizing the importance of the diagnosis in managing these patients.
CONCLUSIONS: In this article, we review a series of cases collected at our center that manifest with extrapulmonary air in the thorax, paying special attention to atypical and uncommon causes. We discuss the causes of extrapulmonary according to its location: mediastinum (spontaneous pneumomediastinum with pneumorrhachis, tracheal rupture, dehiscence of the bronchial anastomosis after lung transplantation, intramucosal esophageal dissection, Boerhaave syndrome, tracheoesophageal fistula in patients with esophageal tumors, bronchial perforation and esophagorespiratory fistula due to lymph-node rupture, and acute mediastinitis), pericardium (pneumopericardium in patients with lung tumors), cardiovascular (venous air embolism), pleura (bronchopleural fistulas, spontaneous pneumothorax in patients with malignant pleural mesotheliomas and primary lung tumors, and bilateral pneumothorax after unilateral lung biopsy), and thoracic wall (infections, transdiaphragmatic intercostal hernia, and subcutaneous emphysema after lung biopsy).

Spontaneous pneumomediastinum is defined as the presence of free air within the mediastinum without an apparent cause such as chest trauma. It is a benign, self-limiting condition that is conservatively treated. Clinical diagnosis is based on two symptoms: chest pain and dyspnea; and on a particular sign: subcutaneous emphysema. It has been reported in patients with influenza A (H1N1) and severe acute respiratory syndrome; however, it has been rarely observed in COVID-19 patients. In this work, we describe six male patients with COVID-19, aged between 27 and 82 years, who presented with spontaneous pneumomediastinum and subcutaneous emphysema; both conditions were completely resorbed with conservative management.
El neumomediastino espontáneo es la presencia de aire libre en el mediastino sin el antecedente de alguna causa como trauma de tórax. Es una condición benigna autolimitada que se trata en forma conservadora. El diagnóstico clínico se basa en dos síntomas: dolor torácico y disnea; y en un signo en particular: enfisema subcutáneo. Ha sido reportado en pacientes con influenza A (H1N1) y síndrome respiratorio agudo grave; sin embargo, ha sido raramente observado en pacientes con COVID-19. En este trabajo describimos seis pacientes del sexo masculino con COVID-19, con edades entre 27 y 82 años, que presentaron neumomediastino espontáneo y enfisema subcutáneo; ambos se reabsorbieron totalmente con manejo conservador.

The use of supraglottic airway devices has been increasing in popularity, mostly due to their high success rate and low complications. However, there is very little information available about the potential and group specific concerns regarding their use in children. We present the first description of a child that developed subcutaneous emphysema after the use of a laryngeal mask. We believe that more awareness to the risk of perioperative adverse events with laryngeal mask insertion in the paediatric population is needed.

Potentially serious complications associated to emergency tracheotomy continue being a matter of concern. We review the pathogenesis of gas leakage in this setting and discuss about the possible mechanisms involved in its cause. We present two cases of pneumomediastinum, subcutaneous emphysema and pneumothorax in the context of emergency tracheotomy under spontaneous ventilation, finally resolved by chest drainage. The combination of overly negative pleural pressures due to extreme inspiratory efforts in the context of an almost completely obstructed airway together with over-pressurized alveoli because of gaseous entrapment secondary to serious expiratory obstruction appears to be the most plausible primary cause of air leaks in our patients. Understanding the underlying mechanisms evolved in its production will help clinicians to suspect and diagnose this phenomenon.