Liver herniation through the foramen of Morgagni: a pitfall in oncologic F-18 FDG PET/CT evaluation of the anterior mediastinum.

Diaphragmatic hernias are characterized by defects in the diaphragm that allow herniation of abdominal contents into the thorax. Herniation through the retrosternal foramen of Morgagni is rare, with less than 300 adult cases reported in the literature. This is a case of a 90-year-old woman who was diagnosed with herniation of the liver through the foramen of Morgagni on F-18 FDG PET/CT scan, which was done for the evaluation of a lung mass. Herniation of liver through the foramen of Morgagni is a potential pitfall in oncologic F-18 FDG PET/CT imaging, as it may mimic any FDG-avid anterior mediastinal mass, benign or malignant, especially in the presence of significant respiratory artifacts that commonly degrade image quality at the lung bases.