[A case of retroperitoneal angiosarcoma effectively treated with recombinant interleukin-2].

Angiosarcoma is rare and highly malignant vascular neoplasm, and primary retroperitoneal angiosarcoma is extremely rare. Preoperative diagnosis is very difficult because there are no specific imaging features, and definitively effective treatment has not yet been established. We recently treated a patient with primary retroperitoneal angiosarcoma in which a prompt and exact diagnosis was difficult to obtain. One month after surgery, local recurrence appeared, but salvage immunotherapy using recombinant interleukin-2 (rIL-2) showed good efficacy, and the patient obtained complete response. Here we report this rare case of angiosarcoma. A 60-year-old woman with abdominal pain was diagnosed with a left retroperitoneal mass on CT scan. The tumor was about 9 cm in diameter and positioned above the left kidney. Further study using MRI, 131I-MIBG scintigraphy, and enhanced CT suggested chronic expanding hematoma and the patient underwent surgical resection. Histopathological diagnosis was primary retroperitoneal angiosarcoma based on positive staining for VIII factor, CD31, CD34, and p53. One month after surgery, FDG-PET revealed local recurrence adjacent to the psoas major. We initiated salvage immunotherapy using rIL-2. The patient was treated effectively and achieved complete response. She is alive and well 19 months after surgery and rIL-2 treatment.