Bochdalek Hernia

•        Explanation:  The incomplete border sign on chest radiograph locates the lesion as extrapulmonary. The differential diagnosis includes loculated pleural fluid, hematoma, lipoma, cyst, pleural plaque, or hernia. CT demonstrates a diaphragmatic hernia in the posterolateral left hemithorax. There is no fat stranding or signs of inflammation in the area to suggest strangulation. Furthermore, there are no signs of acute trauma to the region, despite the history and clinical setting. Absence of other trauma in the region makes traumatic injury to the diaphragm unlikely, as a great deal of force is required to rupture the diaphragm. Isolated traumatic diaphragmatic rupture is therefore extremely unlikely. This diaphragmatic hernia is more likely to be a congenital abnormality in absence of acute findings.

Diagnosis is most likely Bochdalek hernia, which is a congenital diaphragmatic hernia at the posterior attachment of the diaphragm due to failure of the pleuroperitoneal membrane to close in utero.   Congenital diaphragmatic hernias are slightly more common in men. They are most often diagnosed via antenatal screening or in childhood, as they may be associated with pulmonary hypoplasia. Bochdalek hernias are more common on the left side in the posterolateral aspect.

•        Suggested Reading:

Parker MS, Rosado de-Christenson ML, Abbott GF. Pleura, Chest Wall, and Diaphragm: Bochdalek Hernia. In: Chest Imaging Case Atlas, 2^nd edition. Thieme New York 2012; pp. 880-883.