These are being increasingly diagnosed with more widespread use of CT and ultrasound scanning.
Accessory lobes. The livers of the pig, dog and camel are divided into distinct and separate lobes by strands of connective tissue. Occasionally, the human liver may show this reversion and up to 16 lobes have been reported. This abnormality is rare and without clinical significance. The lobes are small and usually on the undersurface of the liver so that they are not detected clinically but are noted incidentally at scanning, operation or necropsy. Rarely they are intrathoracic. An accessory lobe may have its own mesentery containing hepatic artery, portal vein, bile duct and hepatic vein.
This may twist and demand surgical intervention. Ectopic liver. Small nodules of normal liver derived from the embryologic hepatic bud may be found in less than 1% of laparoscopies and autopsies near the gallbladder, hepatic ligaments, gastrorenal ligament, omentum, retroperitorneum
and thorax. These may give rise to hepatocellular carcinoma.
Riedel’s lobe. This is fairly common and is a downward tongue - like projection of the right lobe of the liver.