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.
Many types of blastoma have been linked to a mutation in tumor suppressor genes. For example, pleuropulmonary blastomas have been linked to a coding mutation for p53. However, the mutation which allows proliferation of incompletely differentiated cells can vary from patient to patient and 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 toward malignancy. [1]
Thus, in the case of common blastomas, such as retinoblastomas, a practitioner may go directly into treatment. However, in the case of rarer, more-genetically-linked blastomas, practitioners may karyotype the patient before proceeding with treatment.[ citation needed ] Some examples of blastomas are hepatoblastoma, medulloblastoma, nephroblastoma, neuroblastoma, pancreatoblastoma, pleuropulmonary blastoma, retinoblastoma, glioblastoma multiforme and gonadoblastoma.
Hepatoblastoma (HBL) is the first and most common malignancy in children, often diagnosed during the first 3 years of life. In most cases, HBL is a 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 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. [2]
Brain tumors are the most common type of solid tumors to affect the pediatric population. [3]
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. [4]
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. [5]
The most common type of renal cancer in children is nephroblastoma, also known as Wilms tumor. [6]
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. [7]
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. [8]
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.[ citation needed ]
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. [9]
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. [10]
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. [11]
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. [12]
A brain tumor occurs when abnormal cells form within the brain. There are two main types of tumors: malignant (cancerous) tumors and benign (non-cancerous) tumors. These can be further classified as primary tumors, which start within the brain, and secondary tumors, which most commonly have spread from tumors located outside the brain, known as brain metastasis tumors. All types of brain tumors may produce symptoms that vary depending on the size of the tumor and the part of the brain that is involved. Where symptoms exist, they may include headaches, seizures, problems with vision, vomiting and mental changes. Other symptoms may include difficulty walking, speaking, with sensations, or unconsciousness.
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 found in young children.
Wilms' tumor or Wilms tumor, also known as nephroblastoma, is a cancer of the kidneys that typically occurs in children, and occurs most commonly as a renal tumor in child patients. It is named after Max Wilms, the German surgeon (1867–1918) who first described it.
Glioblastoma, previously known as glioblastoma multiforme (GBM), is the most aggressive and most common type of cancer that originates in the brain, and has very poor prognosis for survival. Initial signs and symptoms of glioblastoma are nonspecific. They may include headaches, personality changes, nausea, and symptoms similar to those of a stroke. Symptoms often worsen rapidly and may progress to unconsciousness.
Sertoli–Leydig cell tumour is a group of tumors composed of variable proportions of Sertoli cells, Leydig cells, and in the case of intermediate and poorly differentiated neoplasms, primitive gonadal stroma and sometimes heterologous elements.
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, pleuropulmonary blastoma and carcinoid tumor were the most common primary tumors. Pleuropulmonary blastoma is regarded as malignant. The male:female ratio is approximately one.
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 diagnosed during a child's first three years of life. Alpha-fetoprotein (AFP) levels are commonly elevated, but when AFP is not elevated at diagnosis the prognosis is poor.
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.
Malignant rhabdoid tumour (MRT) is a very aggressive form of tumour originally described as a variant of Wilms' tumour, which is primarily a kidney tumour that occurs mainly in children.
Mediastinal germ cell tumors are tumors that derive from germ cell rest remnants in the mediastinum. Germ cell tumors most commonly occur in the gonad but occasionally elsewhere.
An atypical teratoid rhabdoid tumor (AT/RT) is a rare tumor usually diagnosed in childhood. Although usually a brain tumor, AT/RT can occur anywhere in the central nervous system (CNS), including the spinal cord. About 60% will be in the posterior cranial fossa. One review estimated 52% in the posterior fossa, 39% are supratentorial primitive neuroectodermal tumors (sPNET), 5% are in the pineal, 2% are spinal, and 2% are multifocal.
Gliosarcoma is a rare type of glioma, a cancer of the brain that comes from glial, or supportive, brain cells, as opposed to the neural brain cells. Gliosarcoma is a malignant cancer, and is defined as a glioblastoma consisting of gliomatous and sarcomatous components. Primary gliosarcoma (PGS) is classified as a grade IV tumor and a subtype of glioblastoma multiforme in the 2007 World Health Organization classification system (GBM). Because of a lack of specific and clear diagnostic criteria, the word "gliosarcoma" was frequently used to refer to glial tumours with mesenchymal properties, such as the ability to make collagen and reticulin.
In histopathology, a small-blue-round-cell tumour, also known as a small-round-blue-cell tumor (SRBCT) or a small-round-cell tumour (SRCT), is any one of a group of malignant neoplasms that have a characteristic appearance under the microscope, i.e. consisting of small round cells that stain blue on routine H&E stained sections.
Virtual karyotype is the digital information reflecting a karyotype, resulting from the analysis of short sequences of DNA from specific loci all over the genome, which are isolated and enumerated. It detects genomic copy number variations at a higher resolution for level than conventional karyotyping or chromosome-based comparative genomic hybridization (CGH). The main methods used for creating virtual karyotypes are array-comparative genomic hybridization and SNP arrays.
Pineoblastoma is a malignant tumor of the pineal gland. A pineoblastoma is a supratentorial midline primitive neuroectodermal tumor. Pineoblastoma can present at any age, but is most common in young children. They account for 0.001% of all primary CNS neoplasms.
The giant-cell glioblastoma is a histological variant of glioblastoma, presenting a prevalence of bizarre, multinucleated giant cells.
Neuro-oncology is the study of brain and spinal cord neoplasms, many of which are very dangerous and life-threatening. Among the malignant brain cancers, gliomas of the brainstem and pons, glioblastoma multiforme, and high-grade astrocytoma/oligodendroglioma are among the worst. In these cases, untreated survival usually amounts to only a few months, and survival with current radiation and chemotherapy treatments may extend that time from around a year to a year and a half, possibly two or more, depending on the patient's condition, immune function, treatments used, and the specific type of malignant brain neoplasm. Surgery may in some cases be curative, but, as a general rule, malignant brain cancers tend to regenerate and emerge from remission easily, especially highly malignant cases. In such cases, the goal is to excise as much of the mass and as much of the tumor margin as possible without endangering vital functions or other important cognitive abilities. The Journal of Neuro-Oncology is the longest continuously published journal in the field and serves as a leading reference to those practicing in the area of neuro-oncology.
A rhabdomyoblast is a cell type which is found in some rhabdomyosarcomas. When found histologically, a rhabdomyoblast aids the diagnosis of embryonal, alveolar, spindle cell/sclerosing, and pleomorphic rhabdomyosarcomas; however, in a tumor, expression of the rhabdomyoblast phenotype is not the only factor in diagnosing a rhabdomyosarcoma. Mesenchymal malignancies can exhibit this phenotype as well. Immunohistochemistry techniques allow for the sensitive detection of desmin, vimentin, muscle specific actin, and MyoD1. Similarly the rhabdomyoblast phenotype can be detected morphologically. Rhabdomyoblasts are early stage mesenchymal cells, having the potential to differentiate into a wide range of skeletal cells. Each stage of differentiation exhibits unique and distinguishable histological characteristics. In its initial from, stellate cells with amphiphilic cytoplasm and ovular central nuclei are observed. Commonly referred to as rhabdoid features, the maturing rhabdomyoblast will likely exhibit low levels of eosinophilic cytoplasm in proximal distances to the nucleus. As maturation and differentiation progress, the cell's cytoplasmic levels of white blood cells increase; additionally, elongated shapes, commonly depicted as “tadpole”, “strap” and "spider cells", are observed. In the concluding phase of differentiation, the white blood cell rich cytoplasm appears bright and exhibits cross-striation. The highly regulated organization of actin and myosin microfilaments in contractile proteins results in this appearance.
In histopathology, a palisade is a single layer of relatively long cells, arranged loosely perpendicular to a surface and parallel to each other. A rosette is a palisade in a halo or spoke-and-wheel arrangement, surrounding a central core or hub. A pseudorosette is a perivascular radial arrangement of neoplastic cells around a small blood vessel.
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