Medial breast margin sign

Last revised by Jeremy Jones on 29 Mar 2022

The medial breast margin sign is a sign of pectus excavatum seen on the frontal chest radiographs of women. It is one of several described signs of pectus excavatum on frontal chest radiographs. 

Radiographic features

Plain radiograph

Women with pectus excavatum may have a more vertically oriented and more sharply defined medial breast borders on frontal x-rays than women with normal chest wall morphology. The medial breast margin sign has been found to have a sensitivity of 48%, specificity of 96%, and a high inter-observer reliability 1.

Visualization of the medial borders of the breasts reflects altered chest wall anatomy in pectus excavatum. With the inward depression of the anterior chest wall, the breasts are more likely to be displaced medially, and the medial borders of the breasts oriented more tangentially to the direction of the x-rays. The breasts of women with pectus exacavatum, instead of slightly diverging, are oriented parallel to each other so that, unless they are touching, their medial borders become more vertical and sharper than they would have been without the anatomical variation.


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Cases and figures

  • Pectus excavatum - medial breast margin sign
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  • Pectus excavatum
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