ABSTRACT
Focal Asymmetry The only mammographic sign of a small invasive cancer may be a non-specifi c asymmetric soft tissue density opacity measuring up to 2 cm diameter and displaying none of the classic signs of malignancy such as spiculation or margin irregularity (7) (Fig. 17.1). A focal asymmetry on standard mammography views is distinguished from a mass lesion because of the absence of defi nite convex outward boarders, usually evident on two orthogonal views. Film readers should pay special attention to the review areas on both the MLO and CC views
in order to perceive such abnormalities (8). The review areas are as follows:
1. A 3-4 cm wide area anterior to the edge of the pectoralis muscle on the lateral oblique view
2. The retro glandular clear space between the posterior margin of the parenchyma and the chest wall on both the MLO and CC projections
3. The medial half of the breast on the CC views 4. The retroareolar area: perception of carcinomas in
this site may be diffi cult because of superimposition of ductal structures and stroma
5. The inferior part of the breast
Having identifi ed a focal asymmetric density, the reader should analyze the following features to decide whether recall for further assessment is indicated.
