The survival rate for rhabdomyosarcoma (RMS) has significantly improved after the introduction of combined multimodality treatment. We report the 20-year treatment outcome of pediatric rhabdomyosarcoma in a single institution. The medical records of 16 patients treated for rhabdomyosarcoma between December 1986 and August 2007 at the Department of Pediatric Surgery, Seoul National University Children's Hospital, were retrospectively reviewed. Mean age at diagnosis was 7.1 years (range: 1.3-14.2 years). Retroperitoneum was the most common primary site (n=7, 43.8%), and embryonal type was predominant (n=11, 6%). Before the treatment, most patients were in advanced TNM stage (stage III 50%, IV; 25%). The patient distribution according to the Intergroup Rhabdomyosarcoma Study Clinical Grouping System (IRS-CGS) was as follows; Group I 31.3%, Group II 12.5%, Group III 31.3% and Group IV 25%. Patients were classified into three groups according to the extent of resection of the primary tumor; complete resection (CR, n=5; 31.3%), gross total resection (GTR, n=7; 43.8%) and incomplete resection (IR, n=4; 25%). Recurrence was observed in 9 patients (56.3%) while there was no recurrence in CR patients. All patients with recurrence were identified as moderate or high-risk according to the IRS-V Risk Group. Pre-treatment TNM stage of RMS in our institution was advanced with aggressive clinical feature, however post-surgical conditions according to IRS-CGS were similar to the previous reports by IRS. This suggests that down-staging of IRS-CGS was achieved with multimodality treatment with CR or GTR. It also suggests that complete resection is the most important prognostic factor in the treatment of RMS in children. Patients classified as moderate or high-risk need close follow-up due to high recurrence rate. In case of localized recurrence, better outcome may be achieved with multimodality treatment including limited surgery.

Pediatric solid tumors have many similarity among different tumors. These tumors present small round cell types, and cause frequent diagnostic problems in pediatric pathology. An important advance in the investigation of these small round cell tumors has been the identification of consistent chromosomal translocations associated with several types of tumor. Eighteen patients with soft tissue sarcoma were available for review. Seventeen cell lines were also included in this study. The RNA from the specimens were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). PAX3-FKHR fusion was present in four of five alveolar rhabdomyosarcoma and PAX7-FKHR fusion was detected in one of five alveolar rhabdomyosarcoma. None of the specimens expressed more than one chimeric transcript. EWS-FLI1 or EWS-ERG fusions were detected in all seven Ewings' sarcoma. No specimens showed EWS-WT1 fusion. These results corresponded well to the histopathologic diagnosis. There were no differences in the histologic appearances of tumors with the more frequent PAX3-FKHR or EWS-FLI1 fusions compared with those containing the variant PAX7-FKHR or EWS-ERG fusions. RT-PCR assay for chimeric transcript is an useful tool for a rapid and
objective
diagnosis of pediatric solid tumors. Through these tools, we can approach genetically to the differential diagnosis of undifferentiated small round tumors.