Medulloblastoma

Medulloblastoma is the most common type of primary brain cancer in children.

In children, the most common type is a malignant medulloblastoma.

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 main parts, the larger cerebrum on top and the smaller cerebellum below towards the back.

Mutations that abnormally activate Sonic hedgehog signaling predispose to cancer of the cerebellum (medulloblastoma) in humans with Gorlin Syndrome and in genetically engineered mouse models.

Positional dizziness and nystagmus are also frequent, and facial sensory loss or motor weakness may be present.

Historically medulloblastomas have been classified as a primitive neuroectodermal tumor (PNET), but it is now known that medulloblastoma is distinct from supratentorial PNETs and they are no longer considered similar entities.

Soon after, the child will develop a stumbling gait, truncal ataxia, frequent falls, diplopia, papilledema, and sixth cranial nerve palsy.

In the past, medulloblastoma was classified using histology, but recent integrated genomic studies have revealed that medulloblastoma is composed of four distinct molecular and clinical variants termed WNT/β-catenin, Sonic Hedgehog, Group 3, and Group 4.

The sonic hedgehog transcription pathway has also been linked to the formation of specific kinds of cancerous tumors, including the embryonic cerebellar tumor, and medulloblastoma, as well as the progression of prostate cancer tumours.

Medulloblastomas are invasive, rapidly growing tumors that, unlike most brain tumors, spread through the cerebrospinal fluid and frequently metastasize to different locations along the surface of the brain and spinal cord.

Metastases of breast cancer, medulloblastoma and prostate cancer all had similar expression patterns of these metastasis-associated genes.

Recurrent mutations in the genes CTNNB1, PTCH1, MLL2, SMARCA4, DDX3X, CTDNEP1, KDM6A, and TBR1 were identified in individuals with medulloblastoma.

Later it was recognized that mutations exist in a significant frequency of medulloblastoma and pancreatic cancers, and in many other tumor subtypes.

Both perivascular pseudorosette and Homer Wright rosette pseudorosette formation are highly characteristic of medulloblastomas, and are seen in up to half of cases.

Examples of tumors containing these are neuroblastoma, medulloblastoma, pinealoblastoma, and primitive neuroectodermal tumors of bone.

Some evidence indicates that proton beam irradiation reduces the impact of radiation on the cochlear and cardiovascular areas and reduces the cognitive late effects of cranial irradiation.

Two prominent examples are pediatric neoplasms (such as medulloblastoma) and prostate cancer.

Medulloblastomas are also seen in Gorlin syndrome as well as Turcot syndrome.

Turcot syndrome is the association between familial polyposis of the colon and brain tumors like medulloblastoma, malignant glioma.

Recurrent mutations in the genes CTNNB1, PTCH1, MLL2, SMARCA4, DDX3X, CTDNEP1, KDM6A, and TBR1 were identified in individuals with medulloblastoma.

Increased nuclear β-catenin levels have also been noted in basal cell carcinoma (BCC), head and neck squamous cell carcinoma (HNSCC), prostate cancer (CaP), pilomatrixoma (PTR) and medulloblastoma (MDB) These observations may or may not implicate a mutation in the β-catenin gene: other Wnt pathway components can also be faulty.

Medulloblastomas are also seen in Gorlin syndrome as well as Turcot syndrome.

Recurrent mutations in the genes CTNNB1, PTCH1, MLL2, SMARCA4, DDX3X, CTDNEP1, KDM6A, and TBR1 were identified in individuals with medulloblastoma.

Mutations in PTCH1 are also associated with medulloblastoma.

Recurrent mutations in the genes CTNNB1, PTCH1, MLL2, SMARCA4, DDX3X, CTDNEP1, KDM6A, and TBR1 were identified in individuals with medulloblastoma.

Mutations of the DDX3X gene are associated with medulloblastoma.

Recurrent mutations in the genes CTNNB1, PTCH1, MLL2, SMARCA4, DDX3X, CTDNEP1, KDM6A, and TBR1 were identified in individuals with medulloblastoma.

Mutations of this gene have also been associated with medulloblastoma.

Correct diagnosis of medulloblastoma may require ruling out atypical teratoid rhabdoid tumor.

Metastatic dissemination via this mechanism has been reported with other brain tumors, including germinomas, medulloblastomas, astrocytomas, glioblastomas, ependymomas, and endodermal sinus tumors.

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 main parts, the larger cerebrum on top and the smaller cerebellum below towards the back.

They are separated by a membrane called the tentorium.

Medulloblastomas are invasive, rapidly growing tumors that, unlike most brain tumors, spread through the cerebrospinal fluid and frequently metastasize to different locations along the surface of the brain and spinal cord.

Metastasis all the way down to the cauda equina at the base of the spinal cord is termed "drop metastasis".

Signs and symptoms are mainly due to secondary increased intracranial pressure due to blockage of the fourth ventricle and tumors are usually present for 1 to 5 months before diagnosis is made.