Detection of common chromosomal translocations in small round blue cell pediatric tumors.
OBJECTIVE
Recurrent and specific chromosomal translocations have been described in four pediatric sarcomas belonging to the small round blue cell (SRBC) group of tumors. Identification of mRNA chimeras using RT-PCR discriminates among alveolar rhabdomyosarcoma (ARMS), Ewing's sarcoma (ES/pPNET), synovial sarcoma (SS) and desmoplastic small round cell tumor (DSRCT); however, frequencies of these translocations are variable. We present a retrospective study comparing histological examination and occurrence of major chromosomal translocations to validate the diagnosis and to assess the frequency of these molecular markers in a group of 92 small round blue cell (SRBC) tumor samples from Hospital Infantil de Mexico.


METHODS
We tested a panel of RT-PCR assays to each RNA tumor sample from formalin-fixed, paraffin-embedded tumors to detect specific mRNA chimeras in 47 ES/pPNET, 19 ARMS, four SS, three DSRCT, and 19 other SRBC tumors.


RESULTS
After excluding poor RNA quality samples, we found translocations in 17/31 ES/pPNET (54.8%), 10/19 ARMS (52.6%), 4/4 SS (100%) and 4/4 DSRCT (100%). We found disagreement in only three samples: one ES/pPNET and one embryonal rhabdomyosarcoma harbor a PAX3-FOXO1 translocation (for ARMS), and one neuroepithelioma harboring a EWS-WT1 (for DSRCT). Unsuitable RNA was found in 20/92 samples (21.7%) and was related to necrosis, small amount of tumor tissue, and use of nitric acid in bone biopsies, but was not related to age of the block.


CONCLUSIONS
We found a significantly lower occurrence of chromosomal translocations in ES/pPNET compared to reports from other groups. Differences may exist in the frequencies of these molecular markers among different populations.
Unidad de Investigación Médica en Enfermedades Infecciosas, Hospital de Pediatría, Instituto Mexicano del Seguro Social, Centro Médico Nacional SXXI, Mexico, D.F., Mexico. Electronic address: vponce@ifc.unam.mx.
M Verónica
MV
Ponce-Castañeda
Unidad de Investigación Médica en Enfermedades Infecciosas, Hospital de Pediatría, Instituto Mexicano del Seguro Social, Centro Médico Nacional SXXI, Mexico, D.F., Mexico.
Adda Jeanette
AJ
García-Chéquer
Departamento de Patología, Hospital Infantil de México Federico Gómez, Secretaría de Salud, Mexico, D.F., Mexico.
Pilar
P
Eguía Aguilar
Unidad de Investigación Médica en Enfermedades Infecciosas, Hospital de Pediatría, Instituto Mexicano del Seguro Social, Centro Médico Nacional SXXI, Mexico, D.F., Mexico.
Marco A
MA
Abundes-Ramírez
Unidad de Investigación Médica en Enfermedades Infecciosas, Hospital de Pediatría, Instituto Mexicano del Seguro Social, Centro Médico Nacional SXXI, Mexico, D.F., Mexico.
Adriana
A
Hernández-Angeles
Departamento de Genética, Hospital General de México, Secretaría de Salud, Mexico, D.F., Mexico.
Karem
K
Nieto-Martínez
Departamento de Genética, Hospital General de México, Secretaría de Salud, Mexico, D.F., Mexico.
Laura
L
Gómez-Laguna
Departamento de Patología, Hospital Infantil de México Federico Gómez, Secretaría de Salud, Mexico, D.F., Mexico.
Stanislaw
S
Sadowinski-Pine
Departamento de Patología, Hospital Infantil de México Federico Gómez, Secretaría de Salud, Mexico, D.F., Mexico.
M de Lourdes
Mde L
Cabrera-Muñoz
D002648:Child; D058405:Desmoplastic Small Round Cell Tumor / Q000235:genetics / Q000473:pathology; D006801:Humans; D018241:Neuroectodermal Tumors, Primitive, Peripheral / Q000235:genetics / Q000473:pathology; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012208:Rhabdomyosarcoma / Q000235:genetics / Q000473:pathology; D012509:Sarcoma / Q000235:genetics* / Q000473:pathology; D012512:Sarcoma, Ewing / Q000235:genetics / Q000473:pathology; D013584:Sarcoma, Synovial / Q000235:genetics / Q000473:pathology; D014178:Translocation, Genetic
Alveolar rhabdomyosarcoma; Chimeric transcripts; Chromosomal translocations; Ewing; RT-PCR; Sarcomas