(P 278) ACUTE CARDIAC CHANGES IN PEDIATRIC AND YOUNG ADULT SOLID TUMOR PATIENTS TREATED WITH TYROSINE KINASE INHIBITORS

Objective: Extraskeletal Ewing sarcoma (EES) are rare forms of soft-tissue sarcoma. Initial staging studies for EES include imaging and bone marrow aspiration and biopsy (BMAB), based on staging for osseous Ewing sarcoma. Recent studies on osseous-based ES have questioned the utility of BMAB compared to modern imaging in detecting metastatic disease. However, no such investigation has investigated the utility of BMAB in EES.

Methods: We reviewed patients at our center with an ESS from 1994 – 2021. Initial diagnostic and staging information including the use of PET scan, bone scan, and BMAB was collected. Metastatic disease at the time of presentation was noted. Patients were excluded if adequate records of their initial diagnosis and staging were not available or if the diagnosis of Ewing sarcoma was not definitive.

Results: Ninety-one patients met criteria for inclusion. Fifty-four patients (59%) underwent BMAB in addition to PET and/or bone scan during their initial workup. Ten (19%) of these patients were found to have metastatic disease at the time of presentation. Sites of metastasis included lung (n=5), bone (n=4), liver (n=1), bowel (n=1), and distant lymph nodes (n=1). These were detected on PET scan in 5 patients, bone scan in 4 patients, and CT Chest in 2 patients. BMAB was negative for marrow involvement in all 54 patients at presentation including those with metastatic disease. Of the 37 patients with no BMAB during their initial workup, 7 (19%) presented with metastatic disease and an additional 12 (32%) later developed metastatic disease. Two of these patients had a negative BMAB after metastatic disease was detected.

Conclusion: The standard utilization of BMAB in the staging process of EES is of low diagnostic yield. BMAB is unlikely to diagnose metastatic involvement even in patients with known metastases to bone.