Spontaneous pneumomediastinum; Time for a consensus.

Dear Editor, Considering the article published by Hülya Dirol and Hakan Keskin: Risk factors for mediastinitis and mortality in Pneumomediastinum,1 I would like to respectfully give my opinion on the so-called spontaneous pneumomediastinum. We agree in dividing pneumomediastinum into primary and secondary, but we consider that the primary is the truly spontaneous or idiopathic, terms that should be omitted and called primary. This pneumomediastinum cannot have any predisposing or precipitating factor. The secondary, can in turn be traumatic and non-traumatic, and the latter is where the predisposing and precipitating factors influence (Figure 1). According to current literature, any pneumomediastinum that is not traumatic is “spontaneous”, but it happens that the group called spontaneous is the one with the greatest triggering cause. This creates confusion and causes conceptual difficulty. We believe that the classification should evolve towards greater accuracy. For us, if a PM has a predisposing factor that compromises the pulmonary structure whether congenital, hereditary, or genetic (bronchiectasis, cystic fibrosis, surfactant alterations, etc.) or acquired (asthma, COPD, interstitial lung disease, COVID-19, etc.), it cannot be spontaneous because there is an underlying predisposing disease. Similarly, the pneumomediastinum that occurs due to a precipitating factor (coughing, labor, intense exercise, use of inhaled drugs, mechanical ventilation, etc.) in a healthy subject or with an underlying lung disease cannot be