Low-grade dysplastic nodule (LGDN) is a premalignant lesion in the cirrhotic liver, positioned between regenerative nodule and high-grade dysplastic nodule on the hepatocarcinogenesis pathway. It is distinguished from regenerative nodule by cellular atypia but carries a low risk of progression to HCC. Typically 10-20 mm in diameter and discovered incidentally during cirrhosis surveillance.
Age Range
40-75
Peak Age
55
Gender
Male predominant
Prevalence
Common
Hepatocarcinogenesis is a multistep process: regenerative nodule → low-grade dysplastic nodule → high-grade dysplastic nodule → early HCC → progressive HCC. In LGDN, mild hepatocyte atypia and clonal proliferation begin but stromal invasion is absent. Portal tract architecture is largely preserved — the nodule still receives portal venous supply and significant neoangiogenesis (unpaired arterial supply) has not yet developed. Therefore, it does not show meaningful arterial phase enhancement. Iron deposition (siderosis) may be seen in some nodules — indicating continued portal blood flow.
A nodule in cirrhotic liver that is T1 hyperintense, T2 isointense/hypointense, shows no arterial phase enhancement, and remains isointense/hyperintense on hepatobiliary phase suggests LGDN. This combination indicates preserved OATP transporter function and absence of neoangiogenesis — early stage on the hepatocarcinogenesis pathway.
Hyperintense signal relative to cirrhotic liver parenchyma on T1-weighted images. Results from intranodular lipid, glycogen, or copper accumulation.
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A nodular lesion demonstrating hyperintense signal on T1-weighted sequences is seen in the cirrhotic liver.
Isointense or mildly hypointense signal on T2-weighted images. T2 hyperintensity is ABSENT — this feature is critical for differentiation from HCC.
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The nodule shows isointense signal to liver parenchyma on T2-weighted sequences with no T2 hyperintensity.
No significant enhancement in arterial phase. Unpaired arterial supply is absent because neoangiogenesis has not yet developed.
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No significant enhancement is observed in the nodule during the arterial phase.
Isointense to liver parenchyma in portal venous phase. No washout — this feature is important in LI-RADS.
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The nodule is isointense to liver parenchyma in the portal venous phase with no washout.
Isointense or mildly hyperintense on hepatobiliary phase with gadoxetic acid. OATP transporters are preserved, so the nodule retains contrast agent.
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The nodule shows isointense signal to liver parenchyma on hepatobiliary phase, suggesting preserved OATP transporter function.
Usually isoattenuating to liver parenchyma on unenhanced CT — difficult to detect by CT. Rarely may be mildly hypoattenuating.
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An isoattenuating nodule to liver parenchyma is seen on unenhanced CT with limited characterization by CT.
Usually hypoechoic or isoechoic nodule on US. Detection is difficult in the heterogeneous parenchyma of cirrhotic liver.
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A hypoechoic nodular lesion is seen on US in the cirrhotic liver; MRI is recommended for further characterization.
Criteria
LGDN containing iron deposition. Shows hypointense signal on T2-weighted and GRE sequences.
Distinct Features
Marked signal loss on T2* GRE (susceptibility effect). Indicates continued portal blood flow — the reticuloendothelial system continues to accumulate iron.
Criteria
LGDN showing marked T1 hyperintensity due to intranodular lipid or glycogen accumulation.
Distinct Features
Signal loss on opposed-phase chemical shift imaging may occur (if intracellular lipid is present). No chemical shift signal loss is expected in glycogen-containing nodules.
Criteria
LGDN that is T1 hyperintense due to copper accumulation. Rarely seen.
Distinct Features
Paramagnetic effect of copper causes T1 shortening. Unlike lipid/glycogen, does not show chemical shift signal loss. May be associated with Wilson disease.
Distinguishing Feature
Regenerative nodule is usually isointense/mildly hyperintense on T1 and <10 mm in size. Distinguished from LGDN by cellular atypia — reliable imaging differentiation is difficult. Size >15 mm favors dysplastic nodule.
Distinguishing Feature
HGDN may begin to show arterial enhancement (neoangiogenesis). Hypointensity on hepatobiliary phase may appear (OATP loss beginning). 'Nodule-in-nodule' pattern indicates HGDN→HCC transformation. These findings are absent in LGDN.
Distinguishing Feature
HCC shows marked arterial phase enhancement + portal/delayed phase washout (APHE + washout = LI-RADS 5). Hypointense on hepatobiliary phase. May be T2 hyperintense. Capsule, mosaic pattern, and portal vein invasion are specific to HCC. LGDN shows none of these findings.
Distinguishing Feature
Focal steatosis shows geographic distribution (segment/lobe-based), not nodular. Shows marked signal loss on chemical shift sequences. Cirrhosis is not required. Normal vessels traversing the steatotic area ('vessel penetration sign') favors focal steatosis.
Urgency
surveillanceManagement
surveillanceBiopsy
Not NeededFollow-up
6-monthLGDN has low malignant potential and biopsy is generally not needed. However, as it is part of the hepatocarcinogenesis process in cirrhotic liver, 6-month MRI follow-up is recommended. During surveillance, size increase, onset of arterial enhancement, or development of hepatobiliary phase hypointensity suggest transformation to HGDN/HCC and require biopsy/multidisciplinary evaluation.
Carries low risk of malignant transformation but should be included in cirrhosis surveillance protocol. No treatment needed, but regular follow-up is recommended for growth or development of APHE. Risk of progression to high-grade dysplasia and subsequently HCC exists.