The lawsuit, filed in the Northern District of Illinois on Dec. 23, claims that the company misled customers since it "does not contain any actual pork rib meat at all."

The suit alleges that McDonald's "knowingly markets the sandwich in a way that deceives reasonable customers," saying that the beloved sandwich has lower quality pork products, including pork shoulder, heart and scalded stomach. Those cuts are less desirable than the premium rib meat.

"The name 'McRib' is a deliberate sleight of hand," the lawsuit claims. "McDonald's willfully, falsely, and knowingly omitted various material facts regarding the quality and character of the McRib — namely, that despite its name and distinctive rib-like shape, it does not actually contain any actual pork rib meat. McDonald's knew these facts would be material to reasonable consumers but still chose not to disclose them."

McDonald's describes the sandwich, which consists of a "pork patty" as "seasoned boneless pork dipped in a tangy BBQ sauce, topped with slivered onions and tangy pickles, all served on a toasted homestyle bun."

The fast food giant released a statement about the suit, which read, "This lawsuit distorts the facts and many of the claims are inaccurate. Food quality and safety are at the heart of everything we do – that's why we're committed to using real, quality ingredients across our entire menu. Our fan-favorite McRib sandwich is made with 100% pork sourced from farmers and suppliers across the U.S. We've always been transparent about our ingredients so guests can make the right choice for them."

The company said it does not permit the use of pork hearts, tripe or scalded stomach in any of its pork products.

The lawsuit seeks class certification for anyone who bought a McRib in the past four years, damages for those members and restitution. It also seeks to stop McDonald's from "further deceptive advertising practices."

McDonald's brings the McRib back to its menu for a limited time, depending on the market.

The McRib sandwich with its distinctive shape is one of the most expensive menu items at the restaurants, according to the lawsuit.