We evaluated the feasibility and usefulness of reverse transcriptase-polymerase 
chain reaction (RT-PCR) on fine-needle aspirates for categorization of small 
blue round cell tumors (SBRCTs). A total of 51 cases, including 25 Ewing 
sarcoma/peripheral primitive neuroectodermal tumors (PNETs), 11 
rhabdomyosarcomas, 13 neuroblastomas, and 2 desmoplastic small round cell tumors 
(DSRCTs) were analyzed. The detection of the EWS-FLI1 (20/25) and EWS-ERG (4/25) 
fusion transcripts resolved 24 of 25 cases of Ewing sarcoma/PNET. The 
PAX3/7-FKHR fusion transcript was detected in 2 of 4 cases of alveolar 
rhabdomyosarcoma and the EWS-WT1 transcript in both cases of DSRCT. Tyrosine 
hydroxylase and 3,4-dihydroxyphenylalanine (dopa) decarboxylase transcripts were 
demonstrated in 10 of 13 cases of neuroblastoma. In comparison, 
immunocytochemical analysis resolved 19 (76%) of 25 Ewing sarcomas, 9 (82%) of 
11 rhabdomyosarcomas, 6 (46%) of 13 neuroblastomas, and 1 (50%) of 2 DSRCTs. 
Overall, RT-PCR resolved 38 (86%) of 44 vs 35 (69%) of 51 cases by 
immunocytochemical analysis. RT-PCR is easily applied to fine-needle aspirates 
of SBRCT and greatly facilitates accurate tumor typing.