Probably just the town of Piotrkow itself, full name now is Piotrkow
Tribunalski. Its very close to Lodz,
and had a high Jewish population, and was a center of Jewish learning
and publication. I suppose there are
other possibilities, such as Pinczow.
You might want to do a JRI-Poland search, and just see which towns
near Lodz come up with family names similar to yours
(assuming you know the names or have a good guess).