Stains from Tissue Paper on Sweater

I would take it to a dry cleaner to see if they can remove the stains.

You could try an Oxy Clean type detergent, but make sure you test the sweater in an inconspicuous spot first. Oxy Clean can be used as a soak or just added to the washer. I just used Oxy Clean to remove 5 yr old baby formula stains on some baby clothes that had been in our attic, and it removed them all after soaking for a few hours in hot water and Oxy Clean. I wouldn't recommend soaking a sweater that way, but perhaps a little thrown in with the wash might help.