Background: The vena azygos lobe is an accessory lobe localized paramediastinally within the right upper lobe underneath a pleural fold running from the pleural apex to the vena azygos. This entity can be seen in approximately 0.4–1% of the population and usually does not cause any symptoms at all. In rare cases inflammatory or poststenotic changes may evolve in this ‘pseudolobe’. Diving accidents frequently occur due to pulmonary
barotrauma caused by local overinflation of lung tissue as a consequence of inappropriate decompression. A diver, however, is prone to experience pulmonary barotrauma, especially if morphologic pulmonary changes
have compromised expiratory air ventilation.
Case report: A 58-year-old male recreational diver experienced cerebrospinal DCS II after a 30 m (99 ft) dive as a result of holding breath inadvertently during decompression and eventually performing an emergency ascent.
Without any delay, the tetraplegic patient was admitted to the nearest hyperbaric chamber administering tables 6a and 5 USN. After referral to our department, NMR imaging revealed punctiform lesions in the white matter
of the brain and the cervico-thoracic spinal cord. In the thoracic CT scan we detected severe bullous changes, especially in the vena azygos lobe, most likely giving rise to pulmonary barotrauma with nearly fatal air-embolism
during decompression. To our knowledge, no such coincidence has been described in the literature.
Conclusions: A vena azygos lobe as a normal anatomical variant does not bear any pathogenic significance for the causation of pulmonary barotrauma with consecutive arterial gas embolism. If, however, a complicated
azygos lobe with a particular distribution of distorted bronchi is present, the diver might be at elevated risk in case of inadequate ascent.

Keywords: Azygos lobe, decompression illness (DCI), pulmonary barotrauma