title: Clinically critical impact of molecular genetic studies in pediatric solid tumors.
abstract: BACKGROUND
  Standard cytogenetic techniques are time-consuming and often not informative with solid tumors. In contrast, the reverse transcriptase-polymerase chain reaction (RT-PCR) is a readily available technique that can rapidly detect tumor-specific chromosomal rearrangements, even in small biopsy specimens. We present cases depicting the importance of including molecular diagnostic studies in the routine evaluation of pediatric solid tumors.
  
  
  METHODS
  We used RT-PCR to detect chimeric transcripts specific for major pediatric solid tumors, including peripheral primitive neuroectodermal tumor (pPNET), alveolar rhabdomyosarcoma (ARMS), and desmoplastic small round-cell tumor (DSRCT). We reviewed six recent cases in which the initial diagnosis was changed by the results of RT-PCR.
  
  
  RESULTS
  Highly unusual or nonspecific clinical and/or histopathologic findings led to the initial diagnoses of neuroblastoma in three patients and DSRCT, leukemia, and carcinoma in one patient each. The final diagnoses after RT-PCR studies were pPNET in three patients, ARMS in two patients, and DSRCT in one patient. RT-PCR results led to early corrections in the diagnosis in two patients, but four patients received treatment not considered optimal for the neoplasms ultimately diagnosed, including three who, despite presenting with localized tumors that have a >70% cure rate with standard therapy, have died or are dying of disease.
  
  
  CONCLUSIONS
  Molecular genetic studies on solid tumors can clarify the diagnosis in seemingly straightforward as well as in overtly problematic cases. These diagnostic distinctions are now critical as disease-specific and risk-directed therapies have emerged.
authors.affiliation: Department of Human Genetics, Pathology, Pediatrics, and Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. kushnerb@mskcc.org
authors.forename: B H
authors.initials: BH
authors.lastname: Kushner
authors.forename: M P
authors.initials: MP
authors.lastname: LaQuaglia
authors.forename: N K
authors.initials: NK
authors.lastname: Cheung
authors.forename: K
authors.initials: K
authors.lastname: Kramer
authors.forename: A C
authors.initials: AC
authors.lastname: Hamelin
authors.forename: W L
authors.initials: WL
authors.lastname: Gerald
authors.forename: M
authors.initials: M
authors.lastname: Ladanyi
mesh_terms: D000293:Adolescent; D014408:Biomarkers, Tumor / Q000096:biosynthesis; D002277:Carcinoma / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D007938:Leukemia / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D008297:Male; D018242:Neuroectodermal Tumors, Primitive / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D011237:Predictive Value of Tests; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018232:Rhabdomyosarcoma, Alveolar / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D018228:Sarcoma, Small Cell / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D014178:Translocation, Genetic / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor