Obscured Mass
An obscured mass is a mass with greater than 25% of its margin hidden by surrounding fibroglandular tissue on mammography; hence, it cannot be fully assessed. This term is commonly used when the portion of the margin that is visualized is circumscribed and it usually implies a lower likelihood of malignancy. If the portion of the visualized margin is microlobulated, indistinct, or spiculated, then these descriptors (which are more suspicious) should take precedence over the descriptor of an “obscured margin,” and that mass would have a higher likelihood of malignancy. This chapter, appearing in the section on asymmetry, mass, and distortion, reviews the key imaging and clinical features, imaging protocols and pitfalls, differential diagnoses, and management recommendations for an obscured mass.