OBJECTIVE: The purpose of this series was to describe the sonographic features of dermato fibrosarcoma protuberans (DP) and correlate them with the pathologic findings of this condition. METHODS: The echogenicity and marginal contour of DP in 4 patients were observed on sonography, and these features were then correlated with the cellular components and histologic grading of pathologic specimens. Additionally, color Doppler sonography was conducted to evaluate the distribution of blood flow signals in the tumors. RESULTS: All lesions were located in the subcutaneous fat layer, abutted against the skin, and had a wide base. Two of the cases of DP observed on the sonograms were hypoechoic, and 2 had mixed echogenicity; however, the mixed echogenic tumors were primarily echoic. The margin was focally lobulated but well defined in the hypoechoic tumors; however, the margin appeared as an irregular pseudopodialike protrusion in the mixed echogenic tumors. Color Doppler sonography showed 2 different blood flow patterns: 1 in which profuse blood flowed through the entire tumor and 1 in which only a small amount of blood flowed through the peripheral portions of the tumor. The 2 blood flow patterns were observed in 1 of each type of tumor. Pathologically, samples corresponding to hypoechoic DP were composed primarily of tumor cells, and samples corresponding to mixed echogenic DP were composed of tumor cells and fibrous tissues. CONCLUSIONS: If a sonogram reveals an oval mass in the subcutaneous tissue that is abutting against the skin and has a focal lobulated margin with hypoechogenicity or an irregular margin with mixed echogenicity, a diagnosis of DP should be considered.