Fox's sign

A non-traumatic ecchymosis over the upper outer or anteromedial thigh, typically located infra-inguinally and parallel to the inguinal ligament, caused by tracking of blood from a retroperitoneal hemorrhage through fascial planes into the thigh.

Causes for retroperitoneal hemorrhage

• Acute hemorrhagic pancreatitis

• Ruptured abdominal aortic aneurysm

• Renal hemorrhage

• Adrenal gland hemorrhage

• Anticoagulant therapy

• Trauma

• Iatrogenic injury after surgery or invasive procedures

• Bleeding disorders