Lewis PR has acquired Piston, a San Diego digital shop with 50 staffers.

Morgan McLintic, executive VP in charge of Lewis' US operations, posted a blog saying the deal deepens the firm's "bench of creative and analytics services."

The firm will add $8.4M in revenues to Lewis, driving its overall business to the $72M mark.

McLintic wrote the strategy of London-based Lewis is "to have the scale in the US to handle any client campaign, and to broaden our digital service proposition."

Piston will become part of Lewis Pulse and operate under its current president & co-founder John Hartman.

Michael Chaney, Piston CEO and co-founder, will take a non-executive post.

Piston serves clients such as AARP, Intuit, Shiseido, SkullCandy, Sunglass Hut, AAA and cars.com.