BackgroundTo determine the accuracy of sonography in diagnosing two common soft tissue tumors, ganglion cysts and lipomas, by simple criteria.Patients and MethodsWe retrospectively reviewed the sonographic images of patients with a palpable soft tissue mass during a 3.5-year period. Soft-tissue tumors were diagnosed as a ganglion cyst, lipoma, or others according to our criteria. A tumor was diagnosed as a ganglion if it fulfilled the following criteria: a well-demarcated, anechoic mass with posterior enhancement, avascularity, and connected to a tendon sheath or a joint capsule on sonography. The diagnostic criteria of a lipoma on sonogram are: a well-demarcated, avascular, subcutaneous mass with internal echogenic lines and parallel long axis to the superficial skin. The sensitivity, specificity, and accuracy of sonographic assessments were determined by comparing them with histological diagnoses. For interobserver variability assessing, we performed kappa statistical analysis by using SPSS software.ResultsThe study population comprised 106 patients. Histological examination yielded 13 ganglion cysts and 35 lipomas. The accuracy of sonography in diagnosing ganglion cysts and lipomas was 96% (69% sensitivity and 100% specificity), and 82% (74% sensitivity and 86% specificity), respectively. The interobserver agreement for tumor margin, shape, echogenicity, and vascularity on a sonogram was 93% (k = 0.47), 72% (k = 0.48), 73% (k = 0.55), and 83% (k = 0.67), respectively.ConclusionsSonography alone is a reliable imaging modality for diagnosing ganglion cysts and lipomas.