This case was sent by my good friend Alberto Villanueva. Muppet made the diagnosis right away (he is gifted!) and wants to share the images with you. They belong to a 17-year-old boy with moderate dyspnea.
PA film shows a small left hemithorax with a triangular opacity at the base (arrows). There is apparent pleural thickening at the apex (
red arrows). Marked mediastinal shifting is seen. On the lateral view, the anterior clear space is much enlarged (arrows).
Fig. 1
Although the radiographic appearance is puzzling, the images are very suggestive of congenital agenesis of the whole left lung (see Mata et al. European Radiology 6:403-414, 1996). In some cases of agenesis, there is marked expansion of the contralateral lung, which herniates through the anterior clear space and occupies the opposite hemithorax, making with the left chest wall. Bronchi and vessels cross the midline (Fig 2 A, B arrows). The triangular opacity at the left base is due to the rotated heart (Fig 2 A, red arrow). The apparent apical pleural thickening is mostly due to expanded extrapleural fat compensating for the volume loss (Fig 2 C, arrow).
Fig. 2
Final diagnosis: congenital agenesis of left lung (atypical presentation)
Congratulations to Xose, who suggested the right diagnosis
Teaching point: usually, agenesis of one lung presents as a white hemithorax with shifting of the mediastinum towards the affected side. Occasionally, the contralateral lung expands markedly, giving the wrong impression of partial volume loss of the affected side, as in the present case.
