Sternalis Muscle on Mammography

IMAGING FINDINGS:​
​Isodense round or flame-shaped mass visible medially at the posterior margin of the CC view

WHY IT MATTERS:

1. Normal anatomic variant seen in 6 - 8 % of women - longitudinal muscle runs along medial edge of pectoralis
2. Characteristic "Aunt Minnie" appearance - no need to get extra views

FURTHER READING:
The Sternalis Muscle: An Unusual Normal Finding Seen on Mammography (AJR 1996)