Malignant liver masses include cancers that originate within the liver (primary liver cancers) and cancers that spread to the liver from other organs (metastatic disease). The liver is one of the most common sites of metastatic spread in the body due to its dual blood supply — receiving blood from both the portal system draining the gastrointestinal tract and the hepatic artery — making it the gateway for dissemination from many GI and non-GI primary tumors. Accurate MRI characterization of liver masses is central to diagnosis, staging, and treatment planning.
Most hepatocellular carcinoma arises in the setting of cirrhosis — making HCC surveillance every 6 months a mandatory component of cirrhosis care. The progression from fatty liver disease to cirrhosis to HCC represents the most important and growing liver cancer pathway in the United States. Benign liver masses — particularly hemangiomas, FNH, and regenerative nodules — must be confidently distinguished from malignant masses using MRI, which can make this determination without biopsy in the majority of cases. Biliary duct obstruction is a frequent complication of cholangiocarcinoma and other perihilar malignancies that must be characterized and urgently addressed.
Causes
Primary liver cancer.
Hepatocellular carcinoma (HCC) is the most common primary liver cancer and the sixth most common cancer worldwide — it is responsible for approximately 800,000 deaths annually. Over 90% of HCC arises in the setting of chronic liver disease or cirrhosis: chronic hepatitis B infection (even without cirrhosis), chronic hepatitis C infection with cirrhosis, alcohol-associated cirrhosis, MASLD/MASH-related cirrhosis — now the fastest growing cause of HCC in the United States — hereditary hemochromatosis, and aflatoxin exposure (a mycotoxin common in sub-Saharan Africa and Southeast Asia). Alpha-fetoprotein (AFP) is elevated in approximately 70% of HCC cases and is used as a surveillance biomarker alongside imaging. Intrahepatic cholangiocarcinoma (ICC) arises from bile duct epithelium within the liver parenchyma — distinct from perihilar (Klatskin tumor) and distal cholangiocarcinoma. ICC risk factors include primary sclerosing cholangitis, hepatolithiasis, liver flukes (Clonorchis sinensis, Opisthorchis viverrini), and chronic viral hepatitis.
Metastatic disease.
Liver metastases are far more common than primary liver cancer in many populations — in Western countries, the liver is a metastatic site in approximately 40% of all cancer patients at autopsy. Primary cancers that most commonly spread to the liver include colorectal cancer (which drains through the portal vein directly to the liver, making hepatic metastasis the dominant pattern of spread), neuroendocrine tumors (which may produce liver metastases that are hypervascular and highly amenable to locoregional therapy), breast, lung, pancreatic, gastric, and melanoma. The pattern of liver metastases on MRI — including their number, size, distribution, signal characteristics, and enhancement pattern — provides important clues about the primary site and guides the choice of systemic therapy.
Symptoms
Early-stage liver malignancies are frequently asymptomatic — the most important reason that surveillance imaging programs for high-risk populations exist. When symptoms develop, they typically reflect either the size of the tumor (right upper quadrant pain, early satiety, abdominal fullness from hepatomegaly) or compromise of liver function (jaundice, coagulopathy, ascites, and encephalopathy in patients with underlying cirrhosis whose remaining liver reserve is further reduced by tumor). Unintentional weight loss, fatigue, and anorexia are constitutional symptoms that suggest advanced disease. In patients with known chronic liver disease, a sudden worsening of liver function, a rising AFP, or the appearance of a new nodule on surveillance ultrasound should trigger urgent MRI evaluation. Paraneoplastic syndromes — including hypoglycemia (from IGF-2 production by HCC) and erythrocytosis (from ectopic erythropoietin) — are recognized but uncommon.
Diagnosis
Evaluation combines serum biomarkers and imaging. AFP, CA 19-9 (elevated in cholangiocarcinoma), and CEA (elevated in colorectal metastases) are obtained based on clinical context. Ultrasound every 6 months is the standard HCC surveillance protocol in cirrhotic patients, but has limited sensitivity for small HCC (approximately 47%) — its primary value is accessibility and cost, not diagnostic accuracy.
An MRI of the abdomen is the most sensitive and specific imaging modality for characterizing liver masses, and the primary staging tool for known liver malignancy. For HCC specifically, the LI-RADS (Liver Imaging Reporting and Data System) framework provides a standardized classification of liver observations in at-risk patients — a LI-RADS 5 observation, defined by the combination of arterial phase hyperenhancement and portal venous or delayed phase washout appearance in a mass over 1 cm in a patient with cirrhosis or chronic hepatitis B, is diagnostic of HCC without biopsy, with specificity exceeding 95%. The "capsule appearance" — a smooth enhancing rim around the mass — further supports the LI-RADS 5 designation. Diffusion-weighted imaging (DWI) identifies restricted diffusion in malignant masses, improving sensitivity for detection of small lesions. Cholangiocarcinoma characteristically shows progressive delayed enhancement (filling in from the periphery) — the inverse of hemangioma enhancement — due to its desmoplastic fibrous stroma. Liver metastases are typically T2-bright with variable enhancement patterns depending on the primary site — colorectal metastases are often hypoenhancing with a targetoid appearance; neuroendocrine metastases are hypervascular. MRI also evaluates vascular invasion (portal vein tumor thrombus vs. bland thrombus), bile duct involvement, lymph node status, and extrahepatic disease extent, all of which are critical for staging and treatment selection.
Classification
Malignant liver masses are classified by cell of origin and stage.
- Hepatocellular carcinoma (HCC): Most common primary liver cancer. Nearly always arises in cirrhosis or chronic viral hepatitis. Staged by the BCLC system (Very Early/Early/Intermediate/Advanced/Terminal) incorporating tumor burden, liver function (Child-Pugh class), and performance status — BCLC stage directly determines treatment eligibility for resection, ablation, TACE, systemic therapy, or transplant.
- Intrahepatic cholangiocarcinoma (ICC): Bile duct-origin liver cancer. Typically presents as a mass-forming type with a fibrous core and peripheral satellite nodules on MRI. Poor prognosis; surgical resection is the only potentially curative treatment. Progressive delayed enhancement pattern is characteristic.
- Liver metastases: The most common liver malignancy overall. Characterized by multiplicity, bilaterality, and variable enhancement depending on primary site. Colorectal liver metastases are uniquely amenable to curative resection when limited to the liver — up to 25–30% of patients with colorectal liver metastases are candidates for resection with curative intent.
- Fibrolamellar HCC: Rare HCC variant occurring in young patients without underlying liver disease. Large fibrous scar on MRI mimics FNH but with different clinical behavior. Better prognosis than conventional HCC.
Treatments
Treatment is highly individualized based on tumor type, BCLC or staging category, underlying liver function, and performance status. Multidisciplinary tumor board review is the standard for treatment planning at experienced centers.
Surgical resection: Hepatic resection offers the best chance of cure for localized HCC with adequate liver reserve (typically Child-Pugh A without portal hypertension), resectable intrahepatic cholangiocarcinoma, and selected colorectal liver metastases. The extent of resection is limited by the volume and function of the remaining liver (future liver remnant) — portal vein embolization can be used preoperatively to induce hypertrophy of the planned remnant, enabling resection of larger tumors.
Liver transplantation.
For patients with HCC within the Milan criteria (one nodule ?5 cm or up to three nodules each ?3 cm, no vascular invasion) in the setting of cirrhosis, liver transplantation treats both the cancer and the underlying liver disease simultaneously, with 5-year post-transplant survival exceeding 70%. Patients are bridged to transplant with locoregional therapy (ablation or TACE) to prevent tumor progression during the waitlist period.
Ablation therapies.
Radiofrequency ablation (RFA) and microwave ablation (MWA) deliver focused thermal energy through a needle electrode or antenna placed directly into the tumor under imaging guidance — producing coagulative necrosis of the lesion. Ablation is curative for HCC lesions under 3 cm and is increasingly used as an alternative to resection for early-stage HCC. Cryoablation freezes tumor tissue and is used for selected lesions. MRI is used to confirm complete ablation and monitor for recurrence.
Transarterial therapies.
HCC derives the majority of its blood supply from the hepatic artery (rather than the portal vein like normal liver), making transarterial delivery of therapy uniquely effective. Transarterial chemoembolization (TACE) combines intra-arterial chemotherapy delivery with embolic particles to simultaneously kill tumor cells and cut off their blood supply — the standard of care for intermediate-stage (BCLC-B) HCC. Transarterial radioembolization (TARE) with Yttrium-90 microspheres delivers targeted internal radiation directly to the tumor. These procedures are planned and monitored with MRI.
Systemic therapy.
Advanced HCC (BCLC-C) is treated with systemic therapy. The combination of atezolizumab (anti-PD-L1) plus bevacizumab (anti-VEGF) has become the standard first-line regimen following the IMbrave150 trial, with overall response rates of 27% and median OS of 19 months — a major advance over sorafenib, which was the only approved systemic option from 2008 to 2020. Durvalumab plus tremelimumab is an alternative first-line combination. Second-line options include lenvatinib, regorafenib, and cabozantinib. Cholangiocarcinoma is treated with gemcitabine plus cisplatin as first-line, with FGFR2 inhibitors (pemigatinib, infigratinib) for FGFR2-fusion positive ICC — present in approximately 15% of cases. Metastatic disease is treated based on the primary cancer histology.
Get an MRI to Confirm Your Diagnosis
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