Liver Masses Part 2
Part 2 review of liver masses for radiology board examinations. Prepare to succeed.
Show Notes/Study Guide:
How do you tell a carcinoid metastasis from a hemangioma on CT or MRI?
Carcinoid will have a continuous rind of enhancement. Hemangioma will show interrupted/discontinuous peripheral enhancement. Also, on board exams with they would almost certainly show you the primary carcinoid tumor in the abdomen/pelvis along with the hepatic metastases.
How to you tell a hemangioma from a hepatic metastasis on board exams?
Look for the T2 bright signal to confirm a hemangioma (CSF bright). Metastases would not be expected to be as bright on T2 weighted images. Both can show interrupted peripheral nodular enhancement. Metastases also may demonstrate a thick rind of enhancement unlike hemangiomas.
What are common imaging manifestations of cholangiocarcinoma?
Cholangiocarcinoma presents as infiltrative hepatic lesion(s) with delayed enhancing soft tissue that grows around and constricts the biliary tree with co-existing peripheral biliary dilatation and contraction of the hepatic capsule. You may also see portal/hepatic vein encasement without visible tumor thrombus unlike HCC which has luminal thrombus and vascular invasion. HCC grows into the portal vein whereas cholangiocarcinoma narrows the portal vein from the outside. If cholangiocarcinoma causes biliary obstruction, you can get bilomas that may have secondary inflammation due to hepatic irritation.
What are some of the common risk factors for development of cholangiocarcinoma?
Elderly males, history of primary sclerosing cholangitis (top risk factor in US), recurrent pyogenic cholangitis, clonorchis sinensis parasitic disease (liver fluke), hepatitis B/C, HIV, alcohol abuse, thorotrast exposure.
What is a Klatskin tumor?
A Klatskin tumor is a cholangiocarcinoma located at the bifurcation of the right and left hepatic ducts, sometimes termed a hilar cholangiocarcinoma. These are aggressive and often obstruct the biliary duct so stricture/narrowing at the bifurcation on MRCP would raise concern for a possible Klatskin tumor.
Are primary sclerosing cholangitis patients at higher risk for developing cholangiocarcinoma or hepatocellular carcinoma?
With PSC risk of cholangiocarcinoma exceeds that of HCC.
What hepatic tumor is most associated with thorotrast exposure?
Hepatic angiosarcoma which is a very rare tumor but the most common primary sarcoma of the liver. Neurofibromatosis and hemochromatosis patients are also at risk for hepatic angiosarcoma.
What MRI contrast agent is predominantly biliary secreted?
Eovist—therefore some centers use this preferentially for liver evaluation, transplant, and biliary leak evaluation.
What are the 2 most common primary hepatic malignancies?
HCC is #1. Cholangiocarcinoma is #2.
Besides hepatic cysts, what are the 2 most common hepatic masses overall?
Metastases are #1. Hemangiomas are #2.
What are the most common primary cancers that metastasize to the liver?
First, I would think of colon cancer. If you see multiple calcified hepatic metastases, think mucinous tumors of the colon, ovary, or pancreas. If you see hypervascular metastases consider melanoma, renal cell carcinoma, carcinoid tumor, islet cell tumor, thyroid and choriocarcinoma.
How does Kaposi sarcoma manifest in the liver and what clinical history do you expect with Kaposi sarcoma?
Always look for an AIDS history with low CD4 count in the question stem whenever considering Kaposi sarcoma. In the liver, Kaposi Sarcoma presents with infiltration of the periportal tissues and may look like biliary dilatation on non-contrast imaging. On post-contrast imaging biliary/periportal nodular enhancement is seen. *If you are presented with what looks like biliary ductal dilatation on a non-contrast CT in a patient with AIDS you always must consider Kaposi Sarcoma for board exam purposes and get a post-contrast scan to see the abnormal enhancement. An alternative history that can raise concern for Kaposi sarcoma is history of organ transplantation with immunosuppression.
How does Kaposi sarcoma present elsewhere in the body?
Kaposi sarcoma can commonly present with purple cutaneous plaques on the legs, and in addition to the liver findings of biliary infiltration with periportal enhancing nodules you can also see pulmonary nodules with mediastinal/hilar nodal enlargement. Remember that lymphoma is on the differential of Kaposi sarcoma and classically gallium 67 would classically show uptake in lymphoma but not in Kaposi sarcoma, whereas thallium 201 would show uptake in both (due to functioning Na/K ATPases in both—thallium is a potassium analogue).
How do you tell a perfusion anomaly from a liver mass or regenerative nodule?
Perfusion anomalies have arterial enhancement without washout and are often wedge shaped and non-mass like in appearance.
