A blastoma is a type of

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

, more common in children, that is caused by malignancies in

precursor cell In cell biology, a precursor cell, also called a blast cell or simply blast, is a partially differentiated cell, usually referred to as a unipotent cell that has lost most of its stem cell properties. A precursor cell is also known as a pro ...

s, often called blasts. Examples are

nephroblastoma Wilms' tumor or Wilms tumor, also known as nephroblastoma, is a cancer of the kidneys that typically occurs in children, rarely in adults.; and occurs most commonly as a renal tumor in child patients. It is named after Max Wilms, the German surge ...

medulloblastoma Medulloblastoma is a common type of primary brain cancer in children. It originates in the part of the brain that is towards the back and the bottom, on the floor of the skull, in the cerebellum, or posterior fossa. The brain is divided into two ...

, and

retinoblastoma Retinoblastoma (Rb) is a rare form of cancer that rapidly develops from the immature cells of a retina, the light-detecting tissue of the eye. It is the most common primary malignant intraocular cancer in children, and it is almost exclusively fo ...

. The suffix ''-blastoma'' is used to imply a tumor of primitive, incompletely differentiated (or precursor) cells, e.g.,

chondroblastoma Chondroblastoma is a rare, benign, locally aggressive bone tumor that typically affects the epiphyses or apophyses of long bones. It is thought to arise from an outgrowth of immature cartilage cells ( chondroblasts) from secondary ossification ...

is composed of cells resembling the precursor of

chondrocyte Chondrocytes (, from Greek χόνδρος, ''chondros'' = cartilage + κύτος, ''kytos'' = cell) are the only cells found in healthy cartilage. They produce and maintain the cartilaginous matrix, which consists mainly of collagen and proteog ...

Molecular biology and treatment

Many types of blastoma have been linked to a mutation in

tumor suppressor A tumor suppressor gene (TSG), or anti-oncogene, is a gene that regulates a cell during cell division and replication. If the cell grows uncontrollably, it will result in cancer. When a tumor suppressor gene is mutated, it results in a loss or red ...

genes. For example,

pleuropulmonary blastoma Pleuropulmonary blastoma (PPB) 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. In a retrospective review of 204 children with lung tumors, pleuro ...

s have been linked to a mutation of the coding for

p53 p53, also known as Tumor protein P53, cellular tumor antigen p53 (UniProt name), or transformation-related protein 53 (TRP53) is a regulatory protein that is often mutated in human cancers. The p53 proteins (originally thought to be, and often s ...

. 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 A karyotype is the general appearance of the complete set of metaphase chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is disce ...

, with a loss of function

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mi ...

on a specific band of

chromosome 13 Chromosome 13 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 13 spans about 114 million base pairs (the building material of DNA) and represents between 3.5 and 4% of the total DNA ...

. This

recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

deletion on the rb gene is also associated with other cancer types and must be present on both

alleles An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...

, for a normal cell to progress towards

malignancy Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

. Thus, in the case of common blastomas, such as

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. Some examples of blastomas are

hepatoblastoma Hepatoblastoma is a malignant liver cancer occurring in infants and children and composed of tissue resembling fetal liver cells, mature liver cells, or bile duct cells. They usually present with an abdominal mass. The disease is most commonly di ...

neuroblastoma Neuroblastoma (NB) is a type of cancer that forms in certain types of nerve tissue. It most frequently starts from one of the adrenal glands but can also develop in the neck, chest, abdomen, or spine. Symptoms may include bone pain, a lump in the ...

pancreatoblastoma Pancreatoblastoma is a rare type of pancreatic cancer. 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 advanc ...

glioblastoma multiforme Glioblastoma, previously known as glioblastoma multiforme (GBM), is one of the most aggressive types of cancer that begin within the brain. Initially, signs and symptoms of glioblastoma are nonspecific. They may include headaches, personality ch ...

and

gonadoblastoma A gonadoblastoma is a complex neoplasm composed of a mixture of gonadal elements, such as large primordial germ cells, immature Sertoli cells or granulosa cells of the sex cord, and gonadal stromal cells. Gonadoblastomas are by definition benign, b ...

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 pediatric brain tumors, classified as a primitive neuroectodermal tumor (PNET) of the cerebellum. Mortality during the first few years after diagnosis is around 15%, although current therapeutic approaches have reached cure rates of up to 60%. The most common forms of therapy are surgical resection, aided by radiation and chemotherapy (before or after surgery), and the survival rates that this yields are between 50% and 90%, a wide range that is influenced by the age at diagnosis, metastasis and histologic variants of the medulloblastoma of each patient. However, despite the long-term survival achieved with current treatments, the neurologic, endocrinologic and cognitive effects are still a great concern in the treatment of medulloblastoma.

Nephroblastoma

The most common type of renal cancer in children is nephroblastoma, also known as Wilms tumor. Nephroblastoma is also the fourth most common pediatric cancer form, and the most common pediatric abdominal cancer, typically diagnosed in children from zero to five years old. The name of this tumor type comes from the man who first described it in 1899, the German physician Dr. Max Wilms. Although the cause for the development of this tumor is still not fully understood, it is hypothesized that it is caused by genetic mutation that alter the embryological development of the genitourinary tract, and some of the genetic markers that have been associated with this process are WT1, CTNNB1, and WTX, which are found in around one third of reported Wilms tumors. There are other genetic markers that have been related to this disease, such as TP53 and MYNC, where TP53 correlates to an overall poorer prognosis.

Neuroblastoma

The most common form of extra-cranial solid tumor in children is neuroblastoma, which represents 8% to 10% of all childhood tumors. About 15% of all cancer-related deaths in the pediatric age group are related to this disease, with incidence of around 10.2 cases per million children younger than 15 years old and 500 new cases reported every year. 90% of these cases are diagnosed before 5 years of age, but 30% of them are found within the first year of life. The median age for the diagnosis of neuroblastoma is 22 months, being rare in adolescence and adulthood but showing poor prognosis when it does present in those age groups. The degree of differentiation of neuroblastoma is correlated to the prognosis, with a wide variety of outcomes (from tumor regression to recurrence and mortality). The standard of care is the use of chemotherapy, surgical resection and radiation, although most aggressive neuroblastomas have demonstrated to be resistant to these therapies.

Pancreatoblastoma

Pancreatoblastoma is a rare form of neoplasia that develops mostly in pediatric patients. This type of malignant neoplasm mimics pancreatic development at 7 weeks of gestation and tends to affect, most commonly, young male children. The usual signs and symptoms for this disease are an abnormal abdominal mass, along with abdominal pain or obstructive jaundice, but these symptoms are not necessarily specific for pancreatoblastoma and make the diagnosis a more complicated process (no standardised guidelines). The aggressiveness of the tumors, biologically speaking, makes them often unresectable at the age of diagnosis, therefore requiring other forms of therapy to help shrink the tumor instead of completely resecting it. Surgical intervention is possible in more localized cases.

Pleuropulmonary blastoma

About 0.5% to 1% of all primary malignant lung tumors are childhood tumors of the lung, making it a rare form of neoplasm. Pleuropulmonary blastoma is one of the three sub-types of these tumors, which include pulmonary blastoma, fetal adenocarcinoma and pleuropulmonary blastoma. Pleuropulmonary blastomas are characterized by the proliferation of malignant immature mesenchymal cells, constituted by two main histological components (mesenchymal and epithelial) that resemble the lung at week 10 to 16 of gestation. The symptoms for this disease are non-specific, and radiologic features are not enough to give a definitive diagnosis and instead require histological analysis.

Retinoblastoma

Retinoblastoma is a rare form of eye neoplasm (found in the retina) that is mostly found in children, being the most common intraocular malignancy of infancy and childhood. The incidence is of one case per every 15,000 to 20,000 live births, and some of the most common symptoms of this disease are leukocoria and strabismus, iris rubeosis, hypopyon, hyphema, buphthalmia, orbital cellulites and exophthalmia. About sixty percent of cases are unilateral and rarely hereditary, although the remaining 40% where cases are either bilateral or multifocal are always related to hereditary mutations. Hereditary retinoblastoma is related to mutations in the RB1 gene, which not only increase the probability of developing retinoblastoma to about 90%, but also increase the probabilities of developing other forms of cancer. Chemotherapy, cryotherapy and brachytherapy are common forms of treatment along with laser, and the prognosis is now excellent for most forms of retinoblastoma.

Glioblastoma multiforme

Glioblastoma multiforme is a form of malignant, grade IV tumor of the central nervous system. Most of diagnosed glioblastoma multiforme cases (around 90% are in fact primary gliomas) arise from normal glial cells by following a multistep oncogenesis process. The remainder are originated from lower grade tumors, and the expansion rate of these is distinctly slower than for primary gliomas. Glioblastoma has been linked to certain genetic alterations and deregulations, but it mostly occurs spontaneously and its progression is associated with deregulation of the G1/S checkpoints, as well as other genetic abnormalities commonly associated with tumor cells. Metastases of this cancer type is not usually reported, and the treatment for this disease often includes full tumor resection along with radiotherapy and chemotherapy. Immunotherapy, as well as integrin signaling pathways inhibitors are also useful for its treatment, and the prognosis depends on the localization of the tumor, the degree of malignancy, genetic profile, proliferation rate and patient's age.

References

{{Reflist Types of neoplasia Pediatric cancers