True accessory / ectopic hepatic lobes are uncommon, with only a few cases being reported in the literature1. This appearance may be due to incomplete atrophy or regression of liver lobes during embryologic development. In almost all cases in the reported literature the finding was misdiagnosed on initial imaging.
Portal venous phase imaging is ideal to discriminate between other differentials, as it will often show a vascular pedicle, which can be missed on non-contrast imaging.
Differentially this could reflect previous traumatic hernia or a congenital hernia, however, the location is atypical and there was no history of trauma.