Round cell sarcoma of the colon with CIC rearrangement

BACKGROUND: The CIC-rearranged sarcoma is a very rare highly aggressive malignant soft tissue group of tumors. It has recently been described as highly aggressive soft tissue tumors of children and young adults sharing similar morphological features with the Ewing sarcoma. The digestive localization is exceptional. CASE PRESENTATION: A 14-year-old male presented with a history of abdominal pain for 1 year, which increased in intensity over the last 2 months. Imaging findings showed a large heterogeneous mesenteric mass on the left flank of the abdomen. Exploratory laparotomy was performed and revealed a large cystic hypervascularized mass depending on the transverse colon and mesocolon. A wide excision of the lesion was performed with segmental colectomy. No postoperative complications were noted. The microscopic examination revealed a vaguely nodular growth of undifferentiated small round cells, arranged in solid sheets separated by thin fibrous septa with a scarce stroma. After an uncomplicated post-operative course, the patient was referred for chemotherapy. The patient died 2 months later with a peritoneal and pleural progression. CONCLUSIONS: The CIC-rearranged sarcoma is an aggressive tumor. There is no standard therapy for this rare disease. Their treatment includes surgery and chemotherapy. Resistance to chemotherapy is common. Further publications and studies will help to determine a standard therapy for this rare disease.