Approach to hepatic masses: Clinical sciences

Hepatic masses are liver lesions that are often found incidentally on imaging performed for unrelated reasons. They can be solid or cystic, and arise from benign, malignant, or infectious etiologies. Most lesions have distinct characteristics on CT or MRI, so understanding these features can help you narrow down your differential diagnoses.

Alright, when a patient presents with a chief concern suggesting a hepatic mass, your first step is to obtain a focused history and physical examination. Most patients with an incidental finding of a liver mass are asymptomatic, but some can have symptoms such as fever, chills, and right upper quadrant abdominal pain. Additionally, patients might report recent travel to foreign countries, or a history of prior malignancy or cirrhosis.

Physical exam is usually unremarkable, but in some cases you might see abdominal distension, right upper quadrant tenderness, a palpable liver edge below the costal margin indicating hepatomegaly, as well as scleral icterus and jaundice.

These clinical features are concerning for a hepatic mass, so your next step is to order a triple-phase abdominal CT with a liver protocol. This type of CT scan uses three phases, arterial, portal venous, and delayed washout phase to better characterize the hepatic lesion. Based on the imaging, hepatic masses are broadly divided into two categories: solid and cystic lesions.

Here’s a clinical pearl! Abdominal duplex ultrasound is an acceptable alternative imaging modality to avoid radiation exposure, particularly in pediatric and pregnant patients. Ultrasound can show whether the mass is solid or cystic, and if there’s vascularity within the lesion.

Okay, let’s talk about solid masses first. Solid liver masses can be benign, but they carry a higher malignant potential than cystic ones. So your work-up should focus on ruling out malignant lesions first. To do that, order a serum alpha fetoprotein, or AFP, which is a marker for liver cancer, and liver function tests.

Let’s discuss the types of malignant lesions, starting with hepatocellular carcinoma, or HCC. HCC is the most common primary cancer of the liver and usually occurs in patients with chronic liver disease. So, history might reveal unintended weight loss and liver cirrhosis from alcohol use disorder, hepatitis B or C infection, or non-alcoholic steatohepatitis, also known as NASH. On labs, AFP will likely be markedly elevated, but LFTs can be elevated or normal.

On CT, you will typically see a hypodense lesion, and on multi-phase imaging you will see an enhancing mass on arterial contrast phase which shows central washout on delayed contrast phase. If these are your findings, you can make your diagnosis of HCC.

Here’s a clinical pearl! HCC is often diagnosed non-invasively with a CT scan using the Liver Imaging Reporting and Data Systems, also known as LI-RADS. This system classifies liver lesions into 5 categories, ranging from definitely benign to definitely HCC based on radiologic characteristics seen on CT. Diagnostic tissue biopsy is not recommended for most cases.

Next, let’s talk about malignant liver metastasis. Metastatic lesions are more common than primary liver cancers, and occur in patients with a history of prior malignancy, particularly breast, colon, and lung cancer. Labs typically show normal AFP and LFTs, although LFTs can be elevated in some cases.

On CT, metastatic lesions typically appear as hypodense lesions with an enhancing peripheral rim and target-like enhancement. These findings support your diagnosis of malignant liver metastasis.

Moving on to intrahepatic cholangiocarcinoma. These arise from epithelial cells of the bile ducts. Although cholangiocarcinoma typically occurs in extrahepatic ducts, it can sometimes be limited to the intrahepatic ducts. Patients may have a history of NASH; hepatitis B or C infection; liver fluke infection; liver cirrhosis; primary biliary cholangitis; primary sclerosing cholangitis; or diabetes mellitus.

Labs will likely show normal serum AFP levels and elevated LFTs in some cases. You can consider ordering additional tumor marker labs such as CEA and CA19-9, which will be elevated, to help you support your diagnosis.

On CT, you can expect to see a hypodense intrahepatic bile duct mass with upstream intrahepatic biliary dilatation which confirms your suspicion. Cholangiocarcinoma, regardless of the location, is associated with very poor prognosis.

Next, let’s talk about hepatic adenoma. This is a benign tumor of the liver often found in patients taking oral contraceptive pills, as well as patients with anabolic steroid use. Patients are often asymptomatic with normal labs. A dedicated liver CT or MRI may show a well-encapsulated solid arterially enhancing hepatic mass. Most hepatic adenomas do not require any intervention unless they are large in size and cause mass effect. However, keep in mind that the mass can rupture, causing bleeding and hemoperitoneum.

Okay, let’s move on to the most common type of benign solid mass, hepatic hemangioma. These arise from a vascular malformation of the liver and can increase in size with exposure to estrogen. Most patients are asymptomatic and usually have normal AFP and LFTs. CT shows peripheral nodular enhancement on arterial phase with centripetal fill-in on delayed phase, supporting your diagnosis of hepatic hemangioma.