How do fibroadenomas appear on imaging?

On mammography, they are usually oval, circumscribed (or obscured), equal density masses. They can develop calcifications over time, often coarse heterogeneous or coarse popcorn-like .
On ultrasound, they typically have homogeneous hypoechoic internal echogenicty.
On MRI, they characteristically are hyperintense on T2-weighted imaging and have non-enhancing internal septations post contrast.