Intimal angiosarcoma of the aorta with tumour embolisation causing mesenteric ischaemia. Report of a case diagnosed using CD31 immunohistochemistry in an intestinal resection specimen.

Primary intimal angiosarcomas of the aorta (i.e. mostly intraluminal sarcomas with evidence of endothelial differentiation) are extraordinarily rare. We report a case in which the diagnosis was accurately made using immunohistochemistry in an intestinal resection specimen and confirmed during autopsy. The patient was a 64-year-old woman with mesenteric ischaemia and a "thrombus" in the abdominal aorta. Two segments of the ileum and the right colon were surgically removed. Histological examination showed multiple tumour emboli in small arteries of the submucosa, serosa and mesentery. The highly atypical cells comprising these emboli were positive immunohistochemically with antibodies to Ulex Europaeus, von Willebrand factor and CD31 and negative for CD34. During post-mortem examination, the intraaortic mass was located around the orifices of the coeliac and the superior mesenteric arteries, and gross tumour thrombi were found in the left renal and splenic arteries. This case emphasises the need for a wide panel of immunohistochemical antibodies when tumour emboli of unknown origin are under study.