Molecularly confirmed primary malignant rhabdoid tumor of the urinary bladder: implications of accurate diagnosis.

Malignant rhabdoid tumors (MRTs) are well recognized in the kidney and extrarenal sites such as soft tissues, retroperitoneum, and bladder but are classified as atypical teratoid/rhabdoid tumors in the central nervous system. The unifying features of both extracranial MRT and atypical teratoid/rhabdoid tumors are the exon deletions/mutations of the SMARCB1 (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1) gene in 22q11.23 and resulting loss of SMARCB1/INI1 (integrase interactor 1) protein expression by immunohistochemistry.

p16INK4A and p14ARF tumor suppressor pathways are deregulated in malignant rhabdoid tumors.

Malignant rhabdoid tumors (MRTs) are aggressive tumors associated with mutations in the SMARCB1 gene. In experimental systems, the loss of SMARCB1 is hypothesized to alter p16(INK4A) pathways resulting in the repression of tumor suppressors. To determine whether these pathways are deregulated in human MRT, we used immunohistochemistry on tissue microarrays to evaluate p16(INK4A)/E2F1/RB and p14(ARF)/MDM2/p53 pathways in 25 atypical teratoid/rhabdoid tumors (AT/RT) and 11 non-CNS MRT.

Spectrum of SMARCB1/INI1 mutations in familial and sporadic rhabdoid tumors.

Background: Germline mutations and deletions of SMARCB1/INI1 in chromosome band 22q11.2 predispose patients to rhabdoid tumor and schwannomatosis. Previous estimates suggested that 15-20% of rhabdoid tumors were caused by an underlying germline abnormality of SMARCB1.

Temporal lobe pleomorphic xanthoastrocytoma and acquired BRAF mutation in an adolescent with the constitutional 22q11.2 deletion syndrome.

DiGeorge syndrome, or velocardiofacial syndrome (DGS/VCFS), is a rare and usually sporadic congenital genetic disorder resulting from a constitutional microdeletion at chromosome 22q11.2. While rare cases of malignancy have been described, likely due to underlying immunodeficiency, central nervous system tumors have not yet been reported.