Have painless mass inner thigh approx 6 x6 cm. quite deep but can move it around. had ruptured baker's cyst on same leg recently. what could it be ?

6cm X 6cm?: That is a relatively large mass. It may be a lipoma if it is soft and freely movable, but without an exam and then a definitive biopsy, it is impossible to know for sure. Due to the sheer size, get it looked at and evaluated by a dr. best wishes.

Many things: It is impossible to tell you what is responsible for your concern without further evaluation. This complaint needs to be evaluated by a provider. It may be a "nothing" or it could be very significant. Please do not delay.

Have it checked.: A Baker's cyst is a pocket of fluid that forms a lump behind the knee. Could be a lipoma, but any mass deserves a physical evaluation.