Molecular genetic testing should be mandatory for the diagnosis of sarcoma and appropriate clinical management, even when histological diagnosis is made by pathologist, according to a study published in the journal The Lancet Oncology.1

Because advancements in molecular genetics of sarcoma have allowed for the identification of type-specific aberrations, researchers sought to evaluate the clinical effect of systematic implementation of molecular assays to improve sarcoma misdiagnosis.

For the multicenter, observational study, researchers enrolled 384 patients recruited from 32 centers of the French Sarcoma Group/Reference Network in Pathology of Sarcomas. Patients had undergone a biopsy or surgical resection for suspicion of dermatofibrosarcoma protuberans, dedifferentiated liposarcoma, Ewing’s sarcoma family of tumors, synovial sarcoma, alveolar rhabdomyosarcoma, or myxoid or round cell liposarcoma.

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All biopsies were reviewed by a sarcoma-expert pathologist, who made 1 primary diagnosis followed by up to 2 differential diagnoses, based solely on histological characteristics. The investigators also made a final diagnosis based on the molecular results.

Results showed that the diagnosis was eventually changed by molecular genetics for 16% of the 50 patients with dermatofibrosarcoma, 23% of the 30 patients with dedifferentiated liposarcoma, and 12% of the 112 with Ewing’s sarcoma family of tumors.

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The diagnosis was also modified for 16% of the 97 patients with synovial sarcoma, 15% of the 46 patients with alveolar rhabdomyosarcoma, and 4% of the 49 patients with myxoid or round cell liposarcoma.

A board of experts determined that misdiagnosis impacted primary management or prognosis assessment in 45 of the 53 cases.


  1. Italiano A, Di Mauro I, Rapp J, et al. Clinical effect of molecular methods in sarcoma diagnosis (GENSARC): a prospective, multicentre, observational study [published online ahead of print March 9, 2016]. Lancet Oncol. doi: 10.1016/S1470-2045(15)00583-5.