Sarcoma With CIC-DUX4Gene Fusion: Case Report of Kidney Tumor Location in a 12-year-old Boy

Recent molecular advances have identified a novel sarcoma defined molecularly by oncogenic fusion of the genes CICand DUX4termed CIC-DUX4sarcomas. The most common site of involvement was the trunk but some cases have been described in the head and neck and extremities. We report one of the first cases of primitive renal CIC-DUX4sarcoma: a 12-year-old boy who presented a renal tumor, a vena cava thrombus, and lung metastases. The morphological and immunohistochemical analysis showed an undifferentiated sarcoma. Molecular analysis demonstrated a CIC-DUX4translocation, confirmed by fluorescence in situ hybridization. Despite treatment with chemotherapy, the evolution was unfavorable and the patient died 17 months after the diagnosis in a context of brain metastases. The diagnosis of sarcoma with CIC-DUX4gene fusion is difficult in lack of specific pathological characteristics emphasizing the need for molecular analysis. Treatment has not yet been codified for these very aggressive tumors.