Genealogy / Legnica - Lignitz and von Liegnitz history [7]

Hi everyone. I'm new here and just doing a little research. I wonder if anyone might know of information on the people who immigrated to the US from Legnica, formerly Liegnitz in Prussia? My mother's maiden name is Lignitz and the only similar name I can find in Europe was a long time ago as von Liegnitz. How did that name morph over time and why do they not exist there anymore (or do they)? Is Lignitz the same lineage as the Prussian royals, von Liegnitz?

Anyway, these are the questions I've been pondering. I appreciate any information you can share.