A blastoma is a type of cancer, more common in children, that is caused by malignancies in precursor cells, often called blasts. Examples are nephroblastoma, medulloblastoma, and retinoblastoma. The suffix -blastoma is used to imply a tumor of primitive, incompletely differentiated (or precursor) cells, e.g., chondroblastoma is composed of cells resembling the precursor of chondrocytes. Molecular biology and treatment Many types of blastoma have been linked to a mutation in tumor suppressor genes. For example, pleuropulmonary blastomas have been linked to a mutation of the coding for p53. However, the mutation which allows proliferation of incompletely differentiated cells can vary from patient to patient and a mutation can alter the prognosis. In the case of retinoblastoma, patients carry a visibly abnormal karyotype, with a loss of function mutation on a specific band of chromosome 13. This recessive deletion on the rb gene is also associated with other cancer types and must be present on both alleles, for a normal cell to progress towards malignancy. Thus, in the case of common blastomas, such as retinoblastomas, a practitioner may go directly into treatment, but in the case of rarer, more-genetically-linked blastomas, practitioners may karyotype the patient before proceeding with treatment. Some examples of blastomas are hepatoblastoma, medulloblastoma, nephroblastoma, neuroblastoma, pancreatoblastoma, pleuropulmonary blastoma, retinoblastoma, glioblastoma multiforme and gonadoblastoma. Types of blastomas Hepatoblastoma Hepatoblastoma (HBL) is the first most common malignancy in children, often diagnosed during the first 3 years of life. In most cases, HBL is an sporadic pathology, although it has been sometimes associated with specific genetic abnormalities such as the Beckwith-Wiedemann syndrome and familial adenomatous polyposis. The incidence has increased over the last three decades, and the risk of developing HBL has been demonstrated to be higher for premature babies with a birth weight of less than 1 kilo. The fact that the survival rate for premature babies has increased might also account for the rise in HBL incidence. The most common signs used for diagnosis are abdominal distention and discomfort, generalized fatigue, loss of appetite and secondary anemia. The most important clinical marker for HBL is serum alpha-fetoprotein (AFP), except in the case of some rare variants of HBL and hepatocellular carcinoma that exhibit lower AFP levels. Medulloblastoma Brain tumors are the most common type of solid tumors to affect the pediatric population. In particular, medulloblastoma is the most common of them, and constitutes about 20% of all the malignant