First Radiologic Description of CIC-FOXO4 Sarcoma: A Case Report of a Rare and Aggressive Sarcoma and Review of the Literature

CIC-rearranged sarcomas are a recently recognized subset of undifferentiated round cell sarcomas, distinct from Ewing sarcoma in both clinical behavior and molecular profile. While CIC-DUX4 is the most described fusion, CIC-FOXO4 is exceedingly rare, with only a handful of reported cases. We report a 47-year-old male with a 3.6 cm intramuscular mass in the left lateral abdominal wall. Molecular testing confirmed a CIC-FOXO4 sarcoma. The lesion was surgically excised and showed predominant epithelioid morphology within a desmoplastic fibrous stroma. The patient is alive with disease, developing three metastatic pulmonary nodules six months after initial presentation, for which he received adjuvant chemotherapy. To our knowledge, this represents the sixth reported case of CIC-FOXO4 sarcoma in the English literature and the first with radiologic description. This case adds to the limited radiologic literature on this rare entity and emphasizes the importance of including CIC-rearranged sarcoma in the differential diagnosis of atypical soft tissue masses.