Beaver Tail Liver: A Rare Anatomic Variant

Beaver tail liver is a rare hepatic anatomical variant in which the left hepatic lobe extends into the left upper quadrant and surrounds the spleen. This extension of the left hepatic lobe consists of normal hepatic parenchyma with no functional liver impairment. In trauma cases, however, the extended left hepatic lobe is vulnerable to injury and confused for a splenic injury due to similar echogenicities and densities on ultrasound and CT. It is also misdiagnosed as a splenic subcapsular hematoma, perisplenic hemorrhage, or mass. Usually, the beaver tail liver is encountered incidentally in patients. We present a 67-year-old male with a history of chronic obstructive lung disease, coronary artery disease, myocardial infarction, and aortic valve replacement. The patient was admitted for further evaluation and placed under the Baker Act for attempting to overdose on oxycodone to commit suicide. Initial imaging identified an ill-defined lesion on CT angiography, which raised concerns for potential malignancy of the liver. Ultimately, an MRI of the abdomen ruled out a malignant lesion due to a lack of abnormal contrast enhancement over the circumscribed region. Consequently, further imaging of the liver led to the incidental discovery of the beaver tail liver in this patient. Due to the rarity of this variant, available literature regarding beaver tail liver is limited to several case reports describing it as an incidental finding. This case highlights the rare nature and unique challenges the beaver tail liver presents for emergency medicine physicians, surgeons, and radiologists interpreting imaging studies without knowledge of its existence. It is important to emphasize how the unexpected presence of the left hepatic lobe in the upper left quadrant of the abdomen can lead to misinterpretations in FAST (focused assessment with sonography in trauma) exams and CT scans. Using non-invasive tools, such as color Doppler, is one way to reduce the incorrect diagnosis of hepatic anatomic variants.