Purpose

Extraskeletal chondrosarcoma is a rare tumor with an indolent course and high propensity for local recurrence and metastasis. This tumor most commonly presents in the proximal extremities of middle-aged males, and is commonly asymptomatic. Although slow growing, these tumors have a significant risk of eventual relapse and metastases, especially to the lung. There are no clinical trials that investigated the best treatment options for this tumor given its very low incidence. The aim of this study is to present the surgical and clinical results of extraskeletal chondrosarcoma, which is a rare tumor.

Background: Chromosomal translocation are frequently observed in leukemias and sarcomas; these translocations break specific genes in the involved chromosomes and create novel chimeric genes that encode a fusion protein. Advances in these techniques have increased knowledge of the genes involved in tumoral development; molecular techniques have enabled more precise diagnosis as well as identification of new prognostic factors. Aims: To explore the use of Reverse-Transcriptase Poly-merase Chain Reaction (RT-PCR) assay for detecting fusion transcripts in a series of Soft Tissue Sarcomas (STS) and compare the results with histopathologic diagnosis. Material and methods: We studied 80 biopsies performed at Orthopaedic Oncology and Reconstructive Surgery Department, CTO-CFR-M.Adelaide Hospital Turin Italy, with clinical suspect of STS. Histological diagnosis was obtained contemporary to evaluation of chimeric transcripts detected by RT-PCR. cDNA were PCR amplified using primer specific for each sarcoma. Paraffin-embedded tissue samples were not used because the poor quality of the extracted RNA may give wrong positive results. Results Histology confirmed 21 Ewing Sarcoma (ES), 14 Synovial sarcoma (SS), 7 Mixoid liposarcoma (M-LPS), 4 Extraskeletal Myxoid Chondrosarcoma (E-MCDS), 4 Dermatofibrosarcoma protuberans (DFSP), 10 Rhabdo-myosarcoma, 10 Leiomyosarcoma. Of the 21 tumors diagnosed as ES, 21 (100%) expressed EWS-FLI1 chimeric transcripts. All 14 SS were positive for SYT-SSX fusion transcripts. Of the 7 cases with diagnosis of M-LPS, six were positive for EWS-CHOP transcripts; of the four cases of E-MCS 3 were positive for EWS-CHN fusion transcripts. All 4 DFSP were positive for COL1A1-PDGFB transcripts. Expression of Myo-D1, tested in ten cases of Rhabdomyosarcoma, was positive while in ten cases of Leiomyosarcoma no expression of Myo-D1 was detected by RT-PCR Ten cases were non sarcoma and negative for molecular biology. Conclusion These results demonstrate a strong concordance between the standard histopathological diagnosis and molecular results. These techniques could be a useful method to increase the quality of histologic diagnosis in difficult cases