Complex sentence: Another type of liver cancer formed by immature liver cells is hepatoblastoma, a rare malignant tumor primarily developing in children, which accounts for approximately 7% of all primary liver cancers.
Split into simpler sentences: Another type of cancer formed by liver cells is hepatoblastoma, which is specifically formed by immature liver cells. It is a rare malignant tumor that primarily develops in children, and accounts for approximately 7% of all primary liver cancers.