Rhabdoid<unk>  The histologic diagnosis of<unk>  depends on identification of characteristic rhabdoid cells—large cells with eccentrically located nuclei and abundant, eosinophilic cytoplasm. However, the histology can be heterogeneous and the diagnosis of<unk>  can often be difficult. Misclassifications can occur. In<unk> s, the INI1 gene (SMARCB1) on chromosome 22q functions as a classic<unk>  suppressor gene. Inactivation of INI1 can occur via deletion, mutation, or acquired UPD. In a recent study, Single nucleotide polymorphism array karyotyping identified deletions or LOH of 22q in 49/51 rhabdoid<unk> s. Of these, 14 were copy neutral LOH (or acquired UPD), which is detectable by SNP array karyotyping, but not by FISH, cytogenetics, or array CGH. MLPA detected a single exon homozygous deletion in one sample that was below the resolution of the SNP array. SNP array karyotyping can be used to distinguish, for example, a medulloblastoma with an isochromosome 17q from a primary rhabdoid<unk>  with loss of 22q11.2. When indicated, molecular analysis of INI1 using MLPA and direct sequencing may then be employed. Once the<unk> -associated changes are found, an analysis of germline DNA from the patient and the parents can be done to rule out an inherited or de novo germline mutation or deletion of INI1, so that appropriate recurrence risk assessments can be made.
Malignant rhabdoid tumour
Primitive neuroectodermal tumor
Atypical teratoid rhabdoid tumor
Endodermal sinus tumor
Pediatric ependymoma
Ameloblastoma
Embryonal rhabdomyosarcoma
Neurothekeoma