Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Hepatoblastoma ?
    ### Response:
    Hepatoblastoma is a rare malignant (cancerous) tumor of the liver that usually occurs in the first 3 years of life. In early stages of the condition, there may be no concerning signs or symptoms. As the tumor gets larger, affected children may experience a painful, abdominal lump; swelling of the abdomen; unexplained weight loss; loss of appetite; and/or nausea and vomiting.
    