Fox's sign

A non-traumatic ecchymosis over the upper outer or anteromedial thigh, typically infra-inguinal and parallel to the inguinal ligament. Caused by tracking of retroperitoneal hemorrhage, classically in acute hemorrhagic pancreatitis, ruptured abdominal aortic aneurysm, or other retroperitoneal bleeding (kidneys, adrenal glands, blood thinners).