Peridiverticulitis of the appendix: an unusual ultrasonic "target lesion".

In a 26-year-old man with perforating diverticulitis of the appendix ultrasonography demonstrated a "target lesion" with a hyperechoic center surrounded by a hypoechoic rim similar to the findings commonly seen in benign and malignant conditions of the gastrointestinal tract. This ultrasonographic appearance is quite different from the ultrasonic findings usual in acute appendicitis. We take this to be the first ultrasonic demonstration of appendiceal diverticulitis, and discuss the clinical features, ultrasonic differential diagnosis, and pathology of this condition.