Mammographic normal variant : the sternalis muscle

D Meerkotter

doi:10.4102/sajr.v13i3.501

Abstract

The imaging findings of a normal variant seen on mammography are presented in this article. The sternalis muscle is an uncommon normal variant, seen only in 8% of cadaveric studies. It is increasingly demonstrated with mammography as imaging techniques improve. This normal variant needs to be differentiated from significant pathology and can pose a diagnostic dilemma. In this article the anatomy of this muscle and the imaging findings are discussed. In selected cases computed tomography (CT) or magnetic resonance imaging (MRI) will be required to investigate the mammographic findings further and these modalities are described regarding the assessment of the sternalis muscle.

Highlights

Mammography is an established screening tool for breast cancer.[1]
When the cranio-caudal view is properly performed, 30 - 40 % of mammograms will reveal the pectoralis muscle.[4]. It is seen as a smooth, convex density along the posterior edge of the image; distinct from this, the sternalis muscle may be visualised as a focal density on the medial aspect of the breast
The sternalis muscle is an unusual normal variant which is seen on occasion on the cranio-caudal view of a mammogram

Summary

Introduction

Mammography is an established screening tool for breast cancer.[1] Early detection of breast cancer has a significant impact on morbidity and mortality.[1] Correct interpretation of mammograms can avoid false negatives and unnecessary biopsies in respect of benign changes. Interpretation of mammograms can be challenging.[2] The medial aspect of the breast is a ‘blind spot’ on the medio-lateral oblique view. More attention is being given to imaging the medial breast, and the sternalis muscle will be revealed with increasing frequency.[2]. A case of the mammographic findings of the sternalis muscle is presented. Features of this normal mammogram variant are described. The computed tomography findings are described and presented.

Case report

Findings

Discussion

Conclusion