Classification of Solid Soft Tissue Tumours by Ultrasonography

Purpose: Malignant soft tissue tumours appear infrequently in comparison to benign lesions. Clinical misdiagnosis leads to inadequate or delayed therapy in many cases of soft tissue sarcoma. The present study explores the question if ultrasonography as a widely-used diagnostic tool allows for a discrimination of benign and malignant soft tissue tumours. Materials and Methods: In a prospective study over a period of 8 years 224 histologically ascertained solid soft tissue tumours, thereof 120 sarcomas and 27 aggressive benign lesions were investigated by B-mode and colour Doppler sonography. The echotexture was analysed computer-based using the parameters echogenicity, homogeneity and vascularisation in all lesions. Results: Different tumour groups showed typical patterns of echotexture, which enabled a classification using 6 categories, distinguishing homogenous hyperechoic, heavily inhomogeneous and homogenous hypoechoic lesions, each group linked to an elevated or low vascularisation. Implementation of the proposed classification revealed a sensitivity in the detection of soft tissue sarcomas and aggressive benign lesions of 94.4% with a specificity of 79.7% and an accuracy of 89.7%. Conclusion: Ultrasonography allows for a determination of the diagnostic and therapeutic procedure in soft tissue tumours. Due to the fact that soft tissue sarcomas present hypervascularised almost exclusively, predominantly homogenous hypoechoic, rarely homogenous hyperechoic, and aggressive benign tumours present homogenous hypoechoic predominantly, such patterns require a biopsy prior to further surgical therapy. However, in homogenous hyperechoic lesions displaying a low blood flow either a primary resection or a conservative treatment with follow-up examinations can be discussed depending on clinical findings and history of the patient. Although the group of heavily inhomogeneous tumours within our collective consisted of benign lesions exclusively, biopsy should be recommended in theses cases in order to exclude a soft tissue sarcoma.