hepatic hemangioma

**Definition/Epidemiology:** The most common benign hepatic tumor (about 5-20% of the population in autopsy/imaging series). It is more common in women (F:M about 3-5:1) and typically presents in adults aged 30-50. Growth may be influenced by estrogen (it can enlarge with pregnancy, OCPs, or estrogen therapy), though this link is not firmly established.

**Pathology:** It is a congenital vascular malformation (not a true neoplasm in many classifications). Grossly it is a well-circumscribed, soft, red-blue, spongy lesion. Microscopically it shows large, dilated (cavernous) vascular spaces lined by a single layer of flat endothelial cells and separated by fibrous septa. Thrombosis, fibrosis, and calcification can occur in larger lesions.

**Clinical features:** - Most are asymptomatic and found incidentally on ultrasound, CT, or MRI. - Giant hemangiomas (>5 cm) can cause RUQ pain, early satiety, or a palpable mass. - Rare complications include spontaneous or traumatic rupture with hemorrhage, and consumptive coagulopathy (Kasabach-Merritt syndrome, which causes thrombocytopenia and DIC; mostly seen in infants with kaposiform hemangioendothelioma or tufted angioma, rarely in giant hepatic hemangiomas). - In infants, hepatic hemangiomas can cause high-output heart failure from AV shunting, hypothyroidism (type 3 iodothyronine deiodinase), and hepatomegaly. - LFTs are usually normal.

**Diagnosis:** - Ultrasound: well-defined, homogeneous, hyperechoic lesion. - Contrast CT or MRI is diagnostic. It shows peripheral, discontinuous, nodular enhancement with progressive centripetal fill-in on delayed images. On T2 MRI it is markedly hyperintense (the "light bulb" sign). - **Do not biopsy**, because of the risk of bleeding. - Tagged RBC scintigraphy is an alternative.

**Management:** - Asymptomatic: observation only; no treatment is needed, and OCPs need not be stopped. - Surgery (enucleation or resection) is reserved for symptomatic lesions, rupture, diagnostic uncertainty, or rapid growth. - Other options include hepatic artery embolization and, rarely, transplant. - Infantile hepatic hemangiomas (GLUT1 positive) may respond to propranolol (and sometimes steroids).

**Key associations/differentials for boards:** - Focal nodular hyperplasia: central stellate scar. - Hepatic adenoma: associated with OCPs and anabolic steroids; risk of rupture/hemorrhage and malignant transformation. - Hepatocellular carcinoma: arterial enhancement with washout. - Hepatic angiosarcoma: associated with vinyl chloride, arsenic, and Thorotrast. - Hemangioma shows peripheral enhancement that fills in; HCC shows arterial enhancement then washout. - Associated with von Hippel-Lindau disease (the hemangioblastoma association is classically CNS/retinal; hepatic hemangiomas are less characteristic).

**High-yield pearl:** Incidental liver lesion in a middle-aged woman with a classic imaging appearance leads to reassurance and observation, with no biopsy.