Differential diagnosis of anechoic/hypoechoic lesions in the abdomen detected by ultrasound

Ultrasound is the method of choice in the detection and differentiation of solid or cystic masses in the abdomen. The differential diagnosis of anechoic and hypoechoic lesions comprises a large variety of benign and malignant diseases or abnormalities. This paper describes a number of such lesions and, in addition, discusses the possible differential diagnoses so far reported in the literature. An attempt is made to describe the different features of such lesions. Most of them are rare but have to be considered if a lesion of unknown origin or clinical relevance is detected by ultrasound.