(P 369) BLAND EMBOLIZATION AS ADJUNCT TREATMENT FOR HEPATIC EPITHELIOID HEMANGIOENDOTHELIOMA

Objective: Epithelioid Hemangioendothelioma (EHE) is rare vascular neoplasm that is unresponsive to chemotherapy, radiotherapy, or immunotherapy. Resection and transplantation are often considered, however recurrence rate after transplantation can be as high as 30% (1). Irreversible electroporation (IRE) has been shown to be a safe and effective approach but is difficult in large or numerous lesions (2). The purpose of this presentation is to explore long-term tumor response after subselective bland embolization of dominant hepatic epithelioid hemangioendothelioma (HEHE).

Methods: An IRB approved retrospective study of patients who underwent bland embolization of liver dominant EHE lesions between 2019 and 2024. This revealed three total patients (1M, 2F) with a total of 8 lesions treated. (Decision to proceed was taken after Multidisciplinary tumor board (MDTB) review. Subsegmental bland embolization was performed using 100-300 micron Embospheres (Merit Medical) until stasis or near stasis was achieved. Preoperative contrast enhanced CT was compared with post operative CT up to four years post-operatively. Volumes of the lesions were obtained using MIMS software by a board certified diagnostic and interventional radiologist with greater than 11 years of experience.

Results: The first case is a 28-year-old male whose single lesion involved segments 4,5, and 8, measuring 14 cm in maximum diameter with a mean volume of 458.1mL. This lesion progressed despite medical treatment with Axitinib and Pembrolizumab. The patient had smaller satellite lesions which had been treated with IRE. One month post embolization CT scan demonstrated a volume of 439.6mL, and four-year follow-up CT demonstrated a volume of 128.9mL, representing a 72% reduction in tumor volume. The second patient is a 54-year-old female who could not finish her IRE treatment sessions due to developing tachyarrhythmias. She had a total of 4 lesions, 2 right-sided and 2 left-sided, which were treated with bland embolization (mean volume 108.8mL, SD 86.1mL). At one month follow up, the mean volume of the lesions was 78.1mL (SD 48.3mL), and at four-year follow-up the mean volume was 9.8mL (SD 8.4mL), representing a 91% reduction in tumor volume. The third patient is a 61-year-old female who presented with numerous, bilobar lesions that would not be amenable to IRE given the distribution and number of lesions. She had a total of 3 lesions treated with bland embolization (mean volume 52.4mL, SD 55.9mL). One month post embolization, CT demonstrated a decrease in size of the lesions with mean volume of 49.9 (SD 49.5mL). Two-year follow up CT demonstrated continued decrease in volumes of the lesions with mean volume of 38.8mL (SD 48.9mL), which represented a 22% reduction in mean tumor volume. There were no grade 3 or above complications after any procedure.

Conclusion: Subsegmental bland embolization with particles is a safe and effective procedure which has the potential to stabilize HEHE that may not otherwise be suitable for surgery or IRE. All patients achieved sustained disease control with majority of lesions demonstrating a partial response. Future directions would be to start a patient registry and obtain more long-term data regarding bland embolization outcomes.

(1) Agrawal N, Parajuli S, Zhao P, Satoskar R, Laurin J, Azumi N, Matsumoto C, Shetty K. Liver transplantation in the management of hepatic epithelioid hemangioendothelioma: a single-center experience and reviewof the literature. Transplant Proc. 2011 Sep;43(7):2647-50. doi: 10.1016/j.transproceed.2011.06.035. PMID:21911139

(2) Neal RE 2nd, Kavnoudias H, Cheung W, Golebiowski B, McLean CA, Thomson KR. Hepatic epithelioidhemangioendothelioma treated with irreversible electroporation and antibiotics. J Clin Oncol. 2013 Sep20;31(27):e422-6. doi: 10.1200/JCO.2012.44.9736. Epub 2013 Jul 29. PMID: 23897957.