ATRT Atypical Teratoid Rhabdoid Tumor
Atypical teratoid rhabdoid tumor or ATRT is a rapidly growing embryonic tumor of the brain and spinal cord.
It is a rare type of tumor, mostly diagnosed in children. It is most often located in the brain, but can be found anywhere else in the central nervous system, including the spinal cord.
In the United States, three children in a million are affected, which makes 30 cases per year. ATRTs represent less than 5% of pediatric cancers of the central nervous system.
The estimated prevalence of ATRT is 1-2% of all CNS tumors in children, and 10-20% of CNS tumors in patients less than three years old. The age-standardized incidence rate is estimated at 1/72,500 individuals / year in Austria.
ATRT occurs from birth to adulthood, with a higher incidence during the first two years of life. Only isolated cases have been reported in adults. Signs of ATRT include macrocephaly, vomiting, irritability, headache, listlessness / lethargy, ataxia, stiff neck, and seizures. It can occur in the posterior fossa, the fourth ventricle, the cerebellar vermis (with intraventricular extension), the cerebellum (alone or associated with a supratentorial tumor), the cerebral hemisphere, the pineal region, the lobe. frontal, brainstem, spinal cord, or have metastasized from a renal rhabdoid tumor.
ATRT can affect the ponto-cerebellar angle (PCA), leading to acute cranial nerve deficits (such as acute facial nerve palsy) as presenting signs.
Etiology (study of causation or origination)
The vast majority of ATRTs exhibit biallelic somatic inactivation of the SMARCB1 gene (22q11.23), a tumor suppressor gene that encodes a key member of the adenosine triphosphate (ATP) chromatin remodeling SWI / SNF complex. It also plays a key role in the regulation of cell proliferation and differentiation. Rarely, mutations are seen in the SMARCA4 gene (19p13.2) encoding another member of the SWI / SNF chromatin remodeling complex.
Diagnosis is based on imaging data (computed tomography and magnetic resonance imaging) revealing large, hyperdense solid tumors associated with marked tumor necrosis, intratumoral hemorrhage, patch-like pattern, associated with adjacent parenchymal edema moderate to pronounced. Intratumoral calcification can be observed. Histological examination of the tumor reveals diffuse growth of predominantly polygonal cells, vesicular nuclei with prominent nucleoli, a strong mitotic index, several cystic or necrosis sites, and scattered cells containing a cytoplasmic hyaline globular inclusion near the nucleus. (rhabdoid cells).
ATRT may be characterized only by rhabdoid cells, or, more frequently, contain areas of rhabdoid cells juxtaposed with areas of primary neuroepithelial cells and / or mesenchymal tissue and / or epithelial tissue. Tumor cells are immunopositive for vimentin, epithelial markers (cytokeratin, epithelial membrane antigen), rarely positive for the mesenchymal marker S-100, and immunonegative for desmin, GFAP (glial fibrillary acid protein), synaptophysin and neurofilaments . The diagnosis is confirmed by the loss of nuclear labeling of the SMARCB1 (or SMARCA4) protein by immunohistochemistry.
The differential diagnosis includes medulloblastoma, ependymoblastoma, primary neuroectodermal tumor, choroid plexus carcinoma, Ewing’s sarcoma, undifferentiated chordoma, anaplastic menengioma, and small cell sarcoma.
ATRT can occur sporadically, or be part of a rhabdoid tumor predisposition syndrome (familial rhabdoid tumor).
Management and treatment
There is no standard treatment for the disease. Treatment includes maximum resection of the tumor mass, and post-surgical chemotherapy and radiotherapy for as long as possible, taking into account the patient’s age.
Treatment of rhabdoid tumor (ATRT)
A combination of treatments may be used to treat rhabdoid tumor.
Surgery is frequently used to treat the rhabdoid tumor. Doctors try to remove as much of the tumor as possible. Sometimes a second surgery is done to remove more or the rest of the tumor. Even if all of the tumor has been removed, chemotherapy and sometimes radiation therapy are usually given after treatment to destroy any remaining cancer cells and reduce the risk of the cancer coming back.
Chemotherapy is usually given after surgery. It can be given in high doses with or without intrathecal chemotherapy. Intrathecal chemotherapy is used to treat what is left of a tumor or a tumor that has spread to a child who is not being treated with radiation therapy.
The following chemotherapeutic agents can be combined in different ways:
- cyclophosphamide (Cytoxan, Procytox)
- cisplatin (Platinol AQ)
- etoposide (Vepesid, VP-16)
- vincristine (Oncovin)
- carboplatin (Paraplatin, Paraplatin AQ)
- ifosfamide (Ifex)
- doxorubicin (Adriamycin)
Radiation therapy is not given to children under 3 years of age. In older children, radiation therapy can be combined with chemotherapy.
There are 2 types of radiotherapy that can be used. Focal radiotherapy is focused directly on the tumor. Craniospinal radiation therapy is given to the skull and spine. Only one or both of these types of radiation therapy can be given to treat the rhabdoid tumor.
High dose chemotherapy with stem cell transplant
High dose chemotherapy and a stem cell transplant may be used to treat the rhabdoid tumor. Stem cells are taken from the blood or bone marrow of the child or a donor for freezing and storage. A high dose of chemotherapy is then given and the child is given the stored stem cells after receiving chemotherapy.
Treatment of recurrent rhabdoid tumor
Recurrent rhabdoid tumor is more likely to come back after treatment in children less than 3 years old.
Chemotherapy is frequently used to treat recurrent rhabdoid tumors. Radiation therapy can also be given if it has not already been done.
ATRT is very aggressive and the prognosis is very poor compared to other malignant brain tumors. Reported survival times vary between 0.5 to 11 months, with a particularly short time for infants.
The word “cancer” is a generic term for a large group of diseases that can affect any part of the body. We also speak of malignant tumors or neoplasms. One of the hallmarks of cancer is the rapid multiplication of abnormal growing cells, which can invade nearby parts of the body and then migrate to other organs. This is called metastasis, which is the main cause of death from cancer. Types of cancer (in alphabetical order of the area concerned):
Information: Cleverly Smart is not a substitute for a doctor. Always consult a doctor to treat your health condition.
Photo credit: National Institutes of Health
Photo descriptions: Anatomy of the brain. The supratentorial area (the upper part of the brain) contains the cerebrum, lateral ventricle and third ventricle (with cerebrospinal fluid shown in blue), choroid plexus, pineal gland, hypothalamus, pituitary gland, and optic nerve. The posterior fossa/infratentorial area (the lower back part of the brain) contains the cerebellum, tectum, fourth ventricle, and brain stem (midbrain, pons, and medulla). The tentorium separates the supratentorium from the infratentorium (right panel). The skull and meninges protect the brain and spinal cord (left panel).