Intimal sarcoma of the descending aorta.

Primary intimal angiosarcoma of the aorta (i.e., mostly intraluminal sarcomas with evidence of endothelial differentiation) is extraordinarily rare. We report a case in which the diagnosis was accurately made using immunohistochemistry in an embolectomy specimen. The patient was a 78-year-old man with a two-month history of bilateral claudication. Doppler ultrasound proved an embolus in both popliteal arteries, which was removed. The highly atypical cells comprising these emboli were positive immunohistochemically for CD68, vimentin, and CD31. Magnetic resonance imaging also showed an irregular tumor (invasion to the left main bronchus). This case emphasizes the need for a wide panel of immunohistochemical studies in tumor emboli of unknown origin.