CIC–DUX4 fusion‐positive round‐cell sarcomas of soft tissue and bone: a single‐institution morphological and molecular analysis of seven cases. Issue 4 (23rd June 2016) - Gambarotti, Marco
Abstract : Aims: Round‐cell sarcomas lacking specific translocations represent a diagnostic challenge. The aim of this study was to describe seven cases of CIC–DUX4 fusion‐positive sarcomas, including the first reported example arising primarily in bone. Methods and results: Patients ranged in age from 15 years to 44 years (median: 33 years). Six cases arose from the soft tissues, and one from the iliac bone. Morphologically, all cases showed an undifferentiated round‐cell population with greater atypia and pleomorphism than Ewing sarcoma. Immunohistochemically, all tumours showed focal and weak positivity for CD99, and five of seven showed nuclear and/or cytoplasmic positivity for Wilms tumour 1. Five patients had lung metastases at presentation. All patients received chemotherapy according to Ewing sarcoma protocols. All but one patient (the one with a bone tumour) died of disease after a mean of 14.5 months from the diagnosis (range: 8–20 months). Conclusions: Our series confirms that CIC–DUX4 fusion‐positive sarcomas are aggressive tumours with an adverse prognosis, and with clinical, histological and genetic differences from Ewing sarcoma. The best therapeutic approach needs to be investigated.