Primary Intracranial CIC-Rearranged Sarcoma With Prior History of B-Cell ALL: A Case Report.

CIC-rearranged sarcoma is a rare, aggressive tumor entity with a dismal outcome. We describe a patient with a history of B-cell acute lymphoblastic leukemia (B-ALL), presenting to our hospital with seizures and left-sided upper limb weakness. Brain imaging revealed a localized right frontal mass, which was surgically resected. Initial pathological analyses suggested a secondary malignant neoplasm, not otherwise specified. However, the tumor's methylome was profiled and analyzed using the DKFZ brain tumor classifier to reach a diagnosis of CIC-rearranged sarcoma, confirmed by FISH study. The patient received the ICE protocol, alongside focal radiotherapy. The patient experienced a local recurrence 14 months post-diagnosis. The brain tumor classifier significantly improved the efficiency of diagnosing this rare tumor in a pediatric patient. However, effective therapeutic regimens for CIC-rearranged sarcomas remain unavailable.