In the case of breast cancer, a well-defined or ill-defined mass may be seen on ultrasound, which is not regular or three-dimensional in shape, with angular or crab-like margins. The tumor has no periphery, but a halo of uneven thickness and high echogenicity can sometimes be seen around the periphery, and the interior tends to be hypoechoic. Most of the masses have tiny calcifications, which are acicular or coarse granular in nature and are diffuse or in clusters. The mass may be poorly demarcated from the skin or pectoral muscle, with edema and thickening of the skin and subcutaneous fat, and disruption of the continuity of the pectoral muscle, with abundant thick blood flow within the tumor and at most margins.