Infantile hepatic hemangioma (IHH) is the most common benign liver tumor of infancy. It is a GLUT1-positive vascular endothelial tumor showing rapid proliferation (0-12 months) followed by slow involution (1-5 years). Three clinical types: focal (solitary, usually asymptomatic), multifocal (multiple nodules, hypothyroidism risk), and diffuse (entire liver involvement, high-output cardiac failure — serious/life-threatening). On US, hypoechoic or heterogeneous mass with increased vascularity and high flow on Doppler. On MR, T2 hyperintense with early peripheral enhancement and progressive centripetal (outside-to-inside) fill — similar to adult hemangioma but faster contrast dynamics. On CT, arterial phase shows avid peripheral enhancement with delayed central fill. Large hemangiomas can cause high-output cardiac failure through arteriovenous shunting. Diffuse type can cause consumptive hypothyroidism (converts T4 to inactive rT3 via type 3 deiodinase). Treatment: focal asymptomatic — observation; symptomatic — propranolol (first-line), corticosteroid, embolization; diffuse — multidisciplinary approach.
Age Range
0-1
Peak Age
0.2
Gender
Female predominant
Prevalence
Uncommon
IHH results from endothelial cell proliferation driven by vascular endothelial growth factor (VEGF). GLUT1 (glucose transporter-1) positivity distinguishes IHH from other vascular anomalies — GLUT1 is also expressed in placental endothelium, suggesting placental stem cell origin. During proliferation phase (0-12 months), endothelial cells rapidly multiply, new vessels form (angiogenesis), and tumor grows. During involution phase (1-5 years), angiogenesis stops, endothelial cells undergo apoptosis, and vascular spaces are replaced by fibrosis and fatty tissue. Pathophysiological basis of imaging findings: US vascularity reflects the tumor's dense vascular architecture — numerous small vascular channels show low-impedance arterial flow. MR T2 hyperintensity results from long T2 relaxation time of slow-flowing blood in vascular spaces. Centripetal enhancement pattern reflects contrast entering from peripheral feeding arteries and slowly filling central vascular spaces — same mechanism as adult hemangioma but faster in IHH (minutes vs hours). Large IHHs can cause high-output cardiac failure through arteriovenous shunting. Diffuse type causes consumptive hypothyroidism through excessive type 3 deiodinase expression.
The signature finding of IHH is early peripheral nodular enhancement with progressive centripetal fill on dynamic contrast MR or CT. This enhancement dynamic shares the same pathophysiological mechanism as adult hepatic hemangioma but completes faster in IHH. This pattern is most prominent during proliferation phase — changes as vascular spaces decrease during involution.
On US, IHH usually appears as a hypoechoic, well-defined mass. With size increase, it may become heterogeneous — central necrosis, hemorrhage, or calcification areas may be seen. Color Doppler shows markedly increased vascularity — dense arterial and venous flow signals within and around the mass. Spectral Doppler detects low-resistance arterial flow (low RI — usually <0.5) and high-velocity venous flow. Hepatic vein and IVC dilation may be seen (increased venous return). In large lesions, abdominal aorta diameter may decrease after celiac trunk (aortic steal phenomenon).
Report Sentence
A hypoechoic/heterogeneous mass measuring ___ × ___ cm in hepatic segment ___ with increased Doppler vascularity and low-resistance arterial flow; findings consistent with infantile hepatic hemangioma.
On MR, IHH shows T1 hypointense and markedly T2 hyperintense signal. T2 hyperintensity reflects slow-flowing blood in vascular spaces and high water content of endothelial cells. Dynamic contrast MR shows early arterial peripheral nodular enhancement with progressive centripetal fill on delayed phases — same pattern as adult hepatic hemangioma but completing faster (minutes vs hours). DWI may show T2 shine-through — high T2 signal creates hyperintense DWI appearance but ADC values are high (no true diffusion restriction).
Report Sentence
On MR, the hepatic mass shows marked T2 hyperintensity with early peripheral enhancement and progressive centripetal fill on dynamic contrast series; consistent with infantile hepatic hemangioma.
On contrast-enhanced CT, IHH shows avid peripheral nodular enhancement in arterial phase — bright enhancing nodules peripherally with central hypodensity. Portal venous and delayed phases show progressive centripetal fill — enhancement progresses from periphery to center. On delayed phase, the entire lesion usually enhances homogeneously. Non-contrast CT shows hypodense lesion. Calcifications may be seen in large lesions (10-20%).
Report Sentence
On contrast-enhanced CT, arterial phase shows peripheral nodular enhancement with progressive centripetal fill on delayed phase.
In large IHHs, high-output flow through arteriovenous shunts leads to cardiac and vascular changes. US shows dilated hepatic veins and IVC (increased venous return). Abdominal aortic diameter may significantly decrease after celiac trunk (aortic steal — blood flow directed to hepatic artery). Cardiomegaly may develop. These findings are most prominent in diffuse type and indicate life-threatening high-output cardiac failure.
Report Sentence
On US, hepatic veins and IVC are dilated with significant aortic diameter decrease after celiac trunk (aortic steal); findings consistent with high-output flow.
On T1-weighted images, IHH appears hypointense — blood in vascular spaces does not have short T1 values. Large feeding arteries and drainage veins show 'flow voids' (signal void on T1 and T2). If hemorrhage is present, T1 hyperintense areas may be seen. During involution phase, T1 signal may increase as fat replacement begins.
Report Sentence
On MR, the hepatic mass shows T1 hypointense signal with flow voids in surrounding vascular structures.
Criteria
Solitary, well-defined mass. Most common type. Usually asymptomatic.
Distinct Features
Spontaneous involution expected. Observation sufficient if asymptomatic. Large focal lesions may cause hepatomegaly and mass effect.
Criteria
Multiple nodules (usually >5). Hypothyroidism risk (type 3 deiodinase). Cutaneous hemangiomas may coexist.
Distinct Features
TSH and free T4 monitoring required. Propranolol effective in symptomatic cases. Involution usually completes.
Criteria
Nearly entire liver involved. Massive hepatomegaly. High-output cardiac failure. Consumptive hypothyroidism. Abdominal compartment syndrome risk.
Distinct Features
LIFE-THREATENING — multidisciplinary approach required. Propranolol + thyroid hormone replacement + embolization + liver transplant if needed. Mortality >80% without treatment.
Distinguishing Feature
Hepatoblastoma is the most common malignant hepatic tumor in infancy. AFP markedly elevated (>1000 ng/mL). MR shows heterogeneous enhancement — no centripetal pattern as in IHH. Hepatoblastoma shows variable T2 signal.
Distinguishing Feature
Adult-type hepatic hemangioma (GLUT1 negative) does not involute and remains stable. IHH (GLUT1 positive) shows proliferation and involution phases. Enhancement pattern is similar but faster in IHH.
Distinguishing Feature
Hepatic metastases in infancy may be from neuroblastoma (stage 4S). US shows multiple hypoechoic or hyperechoic nodules. Urinary catecholamines elevated. IHH shows centripetal enhancement while metastases show peripheral rim or heterogeneous enhancement.
Urgency
urgentManagement
medicalBiopsy
Not NeededFollow-up
3-monthIHH management depends on type and symptom severity. Focal asymptomatic: US surveillance every 3-6 months, involution expected. Symptomatic: propranolol first-line (oral, 1-3 mg/kg/day) — achieves tumor shrinkage via VEGF inhibition and vasoconstriction. Hepatic artery embolization for large lesions. Diffuse type may need high-dose thyroid hormone replacement for consumptive hypothyroidism. Liver transplant as last resort in diffuse type. Biopsy usually unnecessary — imaging provides characteristic findings. However AFP and biopsy should be considered if hepatoblastoma cannot be excluded.
The most common liver tumor of neonates, and the vast majority are benign. However, life-threatening complications can develop in large lesions: high-output cardiac failure (AV shunting), Kasabach-Merritt syndrome, abdominal compartment syndrome. Hypothyroidism should be screened in diffuse type (TSH). GLUT1 positivity distinguishes infantile hemangiomas from congenital hemangiomas (RICH/NICH). Propranolol has revolutionized treatment. AFP monitoring is important for hepatoblastoma exclusion. Most cases show spontaneous involution and do not require surgery.