What is a milk-of-calcium lesion? Is it benign or malignant?

Milk-of-calcium is a benign finding that results from cystic hyperplasia, a type of fibrocystic change. Lobules become cystically dilated, and debris within the fluid calcifies. On a true lateral view (i.e., ML, not MLO), the dependent debris has a linear configuration (teacups). calcifications are often difficult to visualize on the CC view but may be round (pearls) or amorphous.