Hyperechogenic cotton-like patches are the most important ultrasound property of medullary cancer and correspond to amyloid deposits. In contrast with microcalcifications, these foci were larger than 1 mm in diameter, and in contrast with coarse calcifications, they displayed an irregular patchy appearance and did not exhibit a dorsal acoustic shadow in all cases. This is the most specific sonographic sign of medullary carcinoma with a sensitivity of 47%, an odds ratio of 31.5.