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Focal liver lesions: haemangioma, FNH, adenoma, HCC and metastases

The enhancement pattern diagnoses most liver lesions: haemangioma — peripheral nodules filling inward, FNH — uniform arterial enhancement with a central scar, HCC in a cirrhotic liver — arterial enhancement and washout, and metastases — mostly hypovascular.

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Why it matters in the exam

Haemangioma is the commonest solid benign liver tumour. On US — echogenic and well defined; on CT and MRI — discontinuous peripheral nodular enhancement filling inward (centripetal fill-in) and following the blood pool in every phase; very bright on T2. FNH — in a young woman: strong uniform arterial enhancement, a central scar bright on T2 that enhances late, and isodensity to liver in later phases; with hepatobiliary agent (gadoxetate) it stays bright or iso to liver. Hepatocellular adenoma — a woman on the pill, anabolic steroids or glycogen storage disease; risk of bleeding and malignant transformation; dark in the hepatobiliary phase; the HNF1α subtype loses signal on opposed phase because of intracellular fat. Adenoma above 5 cm — resection.

HCC: in a cirrhotic liver or with HBV it can be diagnosed without biopsy. LI-RADS defines major features: enhancement in the late arterial phase (non-rim), washout in the portal or delayed phase, an enhancing capsule and threshold growth. A lesion of 10 mm or more with these features by the size rules is LR-5 — definite HCC. A liver CT or MRI needs at least a late arterial phase, a portal venous phase and a delayed phase. Surveillance in cirrhosis: US every 6 months, with or without AFP. Fibrolamellar HCC — a young patient without cirrhosis, a large mass with a central scar dark on T2 and calcified (unlike the bright scar of FNH).

Metastases: most are hypovascular (colon and gastrointestinal tract) and appear dark in the portal phase and as a "target" on US — a target lesion in the liver is usually a metastasis. Hypervascular metastases: NET, kidney, melanoma, thyroid. Calcified metastases: mucinous colorectal tumours. DWI detects small metastases that are otherwise missed. Cysts: simple cyst — anechoic without enhancement; hydatid cyst — daughter cysts, a detached membrane ("water lily") and a calcified wall; pyogenic abscess — a "cluster" of small cysts coalescing. Biliary hamartomas (von Meyenburg) — many tiny cysts very bright on T2 without biliary communication. Liver lymphoma — multiple hypoechoic lesions.

Key points

• Haemangioma — fills from the edge inward.
• FNH — uniform arterial with a bright scar.
• Adenoma — pill, bleeding, resect above 5 cm.
• HCC — arterial enhancement and washout in cirrhosis.
• Metastases — mostly hypovascular, target lesion.

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Sources

• ACR LI-RADS CT/MRI Core, version 2018 — Major features and categories
• EASL Clinical Practice Guidelines on the Management of Benign Liver Tumours, 2016 — Haemangioma, FNH and hepatocellular adenoma
• AASLD Practice Guidance on Prevention, Diagnosis and Treatment of Hepatocellular Carcinoma, 2023 — Surveillance and non-invasive diagnosis

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.