[Echography in the study of lipomas of superficial soft tissues].

High-resolution sonography (US) was used to evaluate 47 superficial soft tissue lipomas. Forty-one lesions were found in subcutaneous tissues and 6 in superficial muscles. The lipomas were classified by location, shape, echotexture, homogeneity and US beam attenuation values. Moreover, 21 lipomas underwent histology and histologic patterns were correlated with echogenicity. Most lesions were elongated and their greatest diameter was parallel to the skin. Eighty-four percent exhibited well-defined margins. Twenty-six percent of the lipomas were hypoechoic, 24% were isoechoic, 34% hyperechoic and 16% exhibited a mixed pattern. In 27% of cases, a hypoechoic capsule was present. Superficial soft tissue lipomas exhibit unsteady echotexture: most of them are hyperechoic. The correlation between echotexture and histology showed that no typical and steady patterns can be identified, since lipomas vary from a histologic point of view. The clinical diagnosis of superficial lipomas is based on clinical history and the palpation of a well-defined, mobile and soft superficial mass. When palpation is not diagnostic, US can be used to rule out a cyst. An elongated isoechoic or hyperechoic mass in the subcutaneous tissue should suggest a lipoma, whereas a hypoechoic mass is associated with a broader range of differential diagnoses, including malignant tumors. However, malignant masses are not likely to have an elongated or flattened shape. Even though tissue characterization is less specific with US than with CT and MRI, the former method is quick, easy and less expensive and, thanks to high-frequency transducers, is also well-suited to diagnose soft tissue lipomas.