Expansion
A layer of loose areolar tissue between the breast and pectoral fascia
Expansion
The retromammary space is a thin layer of loose areolar tissue separating the posterior surface of the breast from the pectoral fascia. It allows the normal breast to glide freely over the chest wall.
This underlies a standard examination sequence:
- Freely mobile - the lesion is within the breast alone
- Reduced mobility on contracting pectoralis major - the tumour has crossed the retromammary space and involves the fascia or muscle
- Fixed with the muscle relaxed - chest wall involvement, which is stage T4a disease
The same plane is used surgically: it is the natural dissection plane for a mastectomy and the site for submammary placement of a breast implant.