A role for fluorescence in situ hybridization detection of chromosome 22q dosage in distinguishing atypical teratoid/rhabdoid tumors from medulloblastoma/central primitive neuroectodermal tumors.
It has been postulated that infants with medulloblastomas/central primitive neuroectodermal tumors (MB/PNET) may fare worse than older patients because some of them harbor unrecognized atypical teratoid/rhabdoid tumors (AT/RT), rare intracranial neoplasms that are typically unresponsive to therapy and rapidly fatal. Although small primitive cells are common to both entities, chromosome 22q11.2 deletions are common only in AT/RTs. Using fluorescence in situ hybridization (FISH) on archival, paraffin-embedded biopsy tissue with commercially available probes to 22q11.2, the region associated with RTs, we studied 8 cases of AT/RT, 12 cases of MB/PNET, and 4 cases of primitive central nervous system (CNS) neoplasms, which were difficult to classify. 22q Deletions were identified in 6 of 8 (75%) conventional AT/RTs and 0 of 12 (0%) children with classic MB/PNET. Of the 4 originally "difficult to classify" cases, 3 had deletions of 22q. In light of the FISH results, review of the morphology and immunophenotype resulted in 3 tumors being reclassified as AT/RTs and 1 as a large cell MB. These 4 cases highlight the potential diagnostic use of FISH for selected cases of primitive CNS malignancies in children and substantiate the notion that misdiagnosed AT/RTs may, in part account for the worse prognosis associated with "MB/PNET" in children younger than 2 years of age.
Bruch
L A
LA
Department of Pathology (Neuropathology) and Anatomic Pathology, Washington University School of Medicine, St Louis, MO 63110, USA.
Hill
D A
DA
Cai
D X
DX
Levy
B K
BK
Dehner
L P
LP
Perry
A
A
D000293:Adolescent; D016543:Central Nervous System Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D002892:Chromosomes, Human, Pair 22; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D007223:Infant; D008297:Male; D008527:Medulloblastoma / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics; D018242:Neuroectodermal Tumors, Primitive / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics; D011379:Prognosis; D018335:Rhabdoid Tumor / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics; D013724:Teratoma / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics