Fig. 4.6a-f. Infantile hemangioendothelioma. a Shunt vascularity and an enlarged heart in a 4-month-old with a murmur and hepatomegaly. b,c US depicts multiple rounded lesions of heterogeneous echo texture. d Multiple hemangiomas on T2 imaging. e,f Classic early (e), and late (f) contrast enhancement pattern on contrast MR
Fig. 4.7a-d. Mesenchymal hamartoma. a Plain film suggest hepatomegaly; no ascites. b T2 MR image depicts a large cystic lesion with septations. c,d T1 MR confirms the predominantly cystic mesenchymal hamartoma d
Fig. 4.7a-d. Mesenchymal hamartoma. a Plain film suggest hepatomegaly; no ascites. b T2 MR image depicts a large cystic lesion with septations. c,d T1 MR confirms the predominantly cystic mesenchymal hamartoma c a b
Typically, these children will present with a painless abdominal right upper-quadrant mass on routine examination. Other symptoms include vomiting, diarrhea, and weight loss.
Histologically, a single mass involving the left lobe will be seen in 90% of cases. Only 23% of cases will present with a multifocal disease. On histology a lesion with abnormally organized hepatocytes,
Kupffer cells, bile ductules, and well-defined margins are characteristic. All the bile ductules and arterial vessels will be dilatated and multiple fibrotic bands secondary to a central scar will separate the nodules of hepatocytes.
FNH will show a single slightly hypoechoic lesion on US; a central scar may be seen, as well as normal surrounding parenchyma (Carlson et al.
2000). The biliary tree may or may not be dilated (Fig. 4.8a-d).
On unenhanced CT, FNH may appear as isodense or hypodense compared to the liver parenchyma with the presence of a low attenuation central scar. On contrast CT this benign tumor may reveal an enhancement greater than that of the adjacent liver during the early phase (arterial and early portal venous) and may be indistinguishable from adjacent liver in delayed images, indicating rapid washout of contrast material from the lesion. Homogeneous enhancement, smooth surface, a subcapsular location, and ill-defined margins may also be shown (Fig. 4.8e).
As FNH is a tumor with normal hepatic elements, the signal on MRI will be similar to the surrounding liver, showing slightly low signal intensity or an isointense signal on T1 weighted images, and a slightly high signal intensity or isointense signal on T2 weighted images. Usually FNH will present with a central scar, which will be better depicted on T2-weighted images as a high signal lesion. Post-gadolinium images will show an enhancement pattern that resembles that seen on CT (Carlson et al. 2000; MoRtELE et al. 2000) (Fig. 4.8f-g).
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