Epithelioid hemangioendothelioma of the retroperitoneal giant type treated with Toripalimab: A case report.

Epithelioid hemangioendotheliomas (EHEs), low-grade malignant tumors of vascular endothelial cell origin, are characterized by vascular endothelial proliferation. In 2002, the World Health Organization classified EHEs as locally aggressive tumors with the potential to metastasize. Currently, the diagnosis of EHE is based on pathology, histological and immunohistochemical examinations. There are no standard treatment guidelines. We here report a 69-year-old man who presented with left-sided chest and abdominal pain for more than 2 months. Enhanced computed tomography of the thorax and abdomen in another hospital suggested a mass in the left adrenal region that was considered malignant. Positron emission tomography- computed tomography in our hospital suggested a large multi-loculated, hypermetabolic, cystic mass in the left adrenal region that was considered malignant. Accordingly, a puncture biopsy of the mass was performed and the diagnosis of EHE confirmed by pathological examination, including immunohistochemical staining. This patient was treated with the programmed death 1 (PD-1) immune checkpoint inhibitor toripalimab with long-term success. The best response was stable disease (SD) with a progression-free survival (PFS) of more than 13 months. The patient is still alive now. Because the sample size of previous studies was small, further studies are needed to determine the safety and efficacy of toripalimab in the treatment of EHE.