ABSTRACT

Screening mammography requires high-quality images and experienced radiologists. An improved technique with a systematic approach to patient positioning enables visualization of the deep parts of the breast. The sternalis muscle is occasionally observed in mammograms as a variant of the deep normal structures and may mimic a mass. The sternalis muscle is an uncommon anatomic variant of the chest wall musculature. It is located subcutaneously over the pectoralis muscle and has a parallel course to the sternum. It runs from the infraclavicular area to the caudal aspect of the breast. This inconsistent muscle has varying shapes, contours and sizes and may mimic a mass lesion on the craniocaudal (CC) mammogram. Familiarity with its mammographic appearance and ultrasonographic correlation is essential to avoid confusion with a malignant lesion. In this case report, we describe mammographic and ultrasonographic imaging findings of the sternalis muscle and review the literature.