Would Liposuction on the Neck Cause Black Skin to Darken?

This is possible, but not likely.  In my practice, I see color changes very, very infrequently.  If anything, there are hypersensitivity issues, but this usually resolves on its own after a few weeks.  Other things you may notice: waviness, surface irregularities, and loose skin.  

Bruising and inflammation of the skin after Liposuction of the Neck or Chin can cause Black Skin to darken, temporarily. These effects should not be permanent. This may be more common following Ultrasound (Vase) or Laser Liposuction as heat is produced during liposuction.

These post operative changes can cause Post Inflammatory Hyperpigmentation especially in Black Skin. But this phenomena is almost always temporary

You could still have some black an d blue after your liposuction that can last many month after but it should not cause it to darken. Watch my video.