Approach to hepatic masses: Clinical sciences

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Introduction0:00–0:29

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.

Focused H&P0:29–1:55

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 Hepatic Masses1:55–2:19

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.

Hepatocellular Carcinoma2:19–3:39

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.

Malignant Liver Metastasis3:39–4:15

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.

Intrahepatic Cholangiocarcinoma4:15–5:17

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.

Hepatic Adenoma5:17–5:54

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.

Hepatic Hemangioma5:54–6:26

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.Our last solid hepatic mass is focal nodular hyperplasia, or FNH.

Focal Nodular Hyperplasia6:26–6:58

FNH is formed by benign hyperplastic hepatocytes surrounding a central stellate scar. Most patients are asymptomatic and have normal AFP and LFTs.
On CT, you can expect to see bright enhancing mass on arterial phases where you might see a characteristic hypodense central scar resembling a “spoke-wheel” stellate scar.
These findings support your diagnosis of FNH. Now that we’ve discussed the solid lesions, let’s move on to the cystic masses.

Cystic hepatic masses6:58–7:19

Cystic masses of the liver can be benign, malignant, or infectious. So, your next step will include LFTs and specific infectious serologies like amebic and echinococcal tests based on your clinical suspicion.
First, let’s talk about simple cysts, which are the most common cystic liver lesions. Simple cysts are benign and don’t communicate with the biliary tree.

Simple Cysts7:19–8:11

Most are small in size and don’t tend to grow over time. However, large cysts can cause right upper quadrant pain usually from mass effect.
You can expect the labs to be normal and CT scan to show a hypodense thin walled cyst with no internal loculations, confirming the diagnosis of simple cyst.
Here’s a clinical pearl! Ultrasound is a useful initial study that can be used to differentiate between simple cysts and other more complex cysts.
Simple cysts look like a dark anechoic fluid filled mass with thin walls, while complex cysts might show loculations, septations, or internal debris.
Next, we have pyogenic hepatic abscess. These form as a result of bacterial seeding from the portal vein or the biliary tree, so patients with a history of intra-abdominal infections, including cholecystitis and diverticulitis are at a higher risk of developing a pyogenic abscess.

Pyogenic Hepatic Abscess8:11–8:56

Labs can show elevated LFTs in some cases, but echinococcal and amebic serologies will be negative. On CT, expect to see one or multiple rim enhancing cystic structures with irregular borders and hypoattenuation around the rim due to edema.
Also, you might see gas within the abscess for further diagnostic clues, confirming a pyogenic hepatic abscess. Another infectious cystic mass of the liver is an amebic abscess.

Amebic Hepatic Abscess8:56–9:41

The vast majority of amebic abscesses are caused by Entamoeba histolytica and the liver is the most common site of extraintestinal infection.
Patients usually have a history of recent travel to endemic areas like Mexico with a new onset of right upper quadrant pain, fever and diarrhea.
LFTs are elevated in most cases, and a positive amebic serology confirms the diagnosis. On CT, you can expect to see a single rounded mass with an enhancing solid rim and central complex fluid, with the appearance of a double wall that looks like a halo surrounding the primary lesion due to surrounding edema.Alright, moving on to Echinococcal cyst, also known as hydatid cyst.

Echinococcal Hepatic Cyst9:41–10:25

These are formed by Echinococcus tapeworm typically acquired from ingestion of their eggs. Patients often report a history of a recent trip to endemic areas like Central or South America.
Most patients remain asymptomatic until the cyst grows large enough to cause mass effect. LFTs can be elevated, and echinococcal serology will be positive confirming the diagnosis.
CT typically shows a large, well defined, unilocular or multilocular liver cyst with multiple internal “daughter” cysts; and in some cases you may see calcified walls depending on the chronicity of infection.Our final diagnoses are mucinous cystic neoplasms, which include cystadenoma and cystadenocarcinoma.

Mucinous cystic neoplasm10:25–11:51

Both of these neoplasms arise from epithelial cells, but cystadenomas are benign, while cystadenocarcinomas represent malignant and high-grade intraepithelial neoplasia.
Both have similar presentations, with the majority of patients being asymptomatic, with normal or possibly elevated LFTs, and negative infectious serologies.
The main difference can be spotted on CT, where cystadenomas appear as lobulated cystic masses with thin internal enhancing septations, where you may also see internal or peripheral calcifications.On the other hand, a cystadenocarcinoma can also appear as a large multilobulated cystic mass, but it will have more suspicious features, such as enhancing internal solid nodules and thick enhancing septations, and you might also see associated intrahepatic duct dilatation.
However, keep in mind that it can often be hard to differentiate between cystadenoma and cystadenocarcinoma, even on imaging.
Also, the risk of malignant transformation from cystadenoma to cystadenocarcinoma is relatively high. For these reasons, surgical resection with negative margins are generally recommended.
Definitive diagnosis is usually confirmed with postoperative pathology. Alright, as a quick recap… Hepatic masses are broadly divided into solid and cystic lesions based on imaging findings like a dedicated liver CT.

Review11:51–12:28

Solid lesions can be benign or malignant and include HCC, liver metastasis, intrahepatic cholangiocarcinoma, hepatic adenoma, hepatic hemangioma and focal nodular hyperplasia.
Cystic masses can also be benign, malignant, or infectious. They include simple, pyogenic, amebic, and echinococcal cysts, as well as mucinous cystic
Approach to hepatic masses: Video, Steps, and Uses | Osmosis