Hemangiomas are benign liver tumors consisting of (e.g. lacuna-like) dilated blood areas of various sizes and can change degeneratively.
There are capillary or cavernous hemangiomas, different types of vessels can be differentiated (s. literature). The contrast medium sonography of a hemangioma shows the so-called "iris diaphragm phenomenon" (contrast medium intake from peripheral to central). But some hemangioma, especially larger ones, don't show that sign anymore, e.g. due to occurred bleedings, thrombosation, fibrotic restructuring.
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