Blastoma
Encyclopedia
A blastoma is a type of cancer
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, i.e., chondroblastoma is composed of cells resembling the precursor of chondrocytes.
Blastomas usually occur in children.
s 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 retinoblastoma
s, 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.
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
that is caused by malignancies in precursor cells
Precursor cell
In cytology, a precursor cell, also called a blast cell or simply blast, is a type of partially differentiated, usually unipotent cellthat has lost most or all of the stem cell multipotency....
, often called blasts. Examples are nephroblastoma, medulloblastoma
Medulloblastoma
Medulloblastoma is a highly malignant primary brain tumor that originates in the cerebellum or posterior fossa.Previously, medulloblastomas were thought to represent a subset of primitive neuroectodermal tumor of the posterior fossa...
and retinoblastoma
Retinoblastoma
Retinoblastoma is a rapidly developing cancer that develops in the cells of retina, the light-detecting tissue of the eye. In the developed world, Rb has one of the best cure rates of all childhood cancers , with more than nine out of every ten sufferers surviving into...
The suffix blastoma is used to imply a tumor of primitive, incompletely differentiated (or
precursor) cells, i.e., chondroblastoma is composed of cells resembling the precursor of chondrocytes.
Blastomas usually occur in children.
Molecular biology and treatment
Many types of blastoma have been linked to a mutation in tumor suppressor genes. For example pleuropulmonary blastomaPleuropulmonary blastoma
Pleuropulmonary blastoma is a rare cancer originating in the lung or pleural cavity. It occurs most often in infants and young children but also has been reported in adults...
s have been linked to a mutation of the coding for p53
P53
p53 , is a tumor suppressor protein that in humans is encoded by the TP53 gene. p53 is crucial in multicellular organisms, where it regulates the cell cycle and, thus, functions as a tumor suppressor that is involved in preventing cancer...
. 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
Karyotype
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...
, with a loss of function mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
on a specific band of chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
13. This recessive
Recessive
In genetics, the term "recessive gene" refers to an allele that causes a phenotype that is only seen in a homozygous genotype and never in a heterozygous genotype. Every person has two copies of every gene on autosomal chromosomes, one from mother and one from father...
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 retinoblastoma
Retinoblastoma
Retinoblastoma is a rapidly developing cancer that develops in the cells of retina, the light-detecting tissue of the eye. In the developed world, Rb has one of the best cure rates of all childhood cancers , with more than nine out of every ten sufferers surviving into...
s, a practitioner may go directly into treatment, but in the case of rarer, more genetically linked blastomas, practitioners may karyotype
Karyotype
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...
the patient before proceeding with treatment.
Types of blastomas
- HepatoblastomaHepatoblastomaHepatoblastoma is an uncommon malignant liver neoplasm occurring in infants and children and composed of tissue resembling fetal or mature liver cells or bile ducts. Affecting 1 in 1.5 million. They are usually present with an abdominal mass...
- MedulloblastomaMedulloblastomaMedulloblastoma is a highly malignant primary brain tumor that originates in the cerebellum or posterior fossa.Previously, medulloblastomas were thought to represent a subset of primitive neuroectodermal tumor of the posterior fossa...
- Nephroblastoma
- NeuroblastomaNeuroblastomaNeuroblastoma is the most common extracranial solid cancer in childhood and the most common cancer in infancy, with an annual incidence of about 650 cases per year in the US , and 100 cases per year in the UK . Close to 50 percent of neuroblastoma cases occur in children younger than two years old...
- PancreatoblastomaPancreatoblastomaPancreatoblastoma is a rare tumor of the pancreas.It occurs mainly in childhood and has a relatively good prognosis.-Symptoms:Children with pancreatoblastoma rarely present with early-stage disease, instead, most present with locally advanced or metastatic disease. Common presenting symptoms...
- Pleuropulmonary blastomaPleuropulmonary blastomaPleuropulmonary blastoma is a rare cancer originating in the lung or pleural cavity. It occurs most often in infants and young children but also has been reported in adults...
- RetinoblastomaRetinoblastomaRetinoblastoma is a rapidly developing cancer that develops in the cells of retina, the light-detecting tissue of the eye. In the developed world, Rb has one of the best cure rates of all childhood cancers , with more than nine out of every ten sufferers surviving into...