Renowned Pennsylvania portrait artist Nelson Shanks has painted everyone from Princess Diana to Pope John Paul II, along with celebrities, such as Marisa Tomei.

On a recent Friday, Shanks, 77, revealed to the Philadelphia Daily News that his portrait of President Bill Clinton includes a hidden secret -- a nod to Monica Lewinsky's stained blue dress that became a piece of evidence in Ken Starr's special investigation of the 42nd president.

Lewinsky, you may remember, was the former White House intern who had an affair with Clinton while he was in the Oval Office.

Shanks said when he was commissioned to paint Clinton, he could never get the Monica incident completely out of his mind and subtly incorporated it in the painting.

"If you look at the left-hand side of it there's a mantel in the Oval Office and I put a shadow coming into the painting and it does two things. It actually literally represents a shadow from a blue dress that I had on a mannequin that I had there while I was painting it, but not when he was there. It is also a bit of a metaphor in that it represents a shadow on the office he held, or on him," said Shanks.

This is not the first hint of controversy the painting has caused. The portrait raised eyebrows when it was unveiled nine years ago because Clinton's wedding ring was missing.

Clinton reportedly chose Shanks to paint the portrait back in 2001 which has been on display at The National Portrait Gallery in Washington, D.C. It's one of 55 images of the former President that rotate on and off display, spokeswoman Bethany Bentley told the Associated Press.

Lewinsky has not commented on Shanks' revelation about the portrait.

The former White House intern has been busy as a Vanity Fair contributor. In May 2014, the magazine interviewed Lewinsky, 40, who gave exclusive details about the affair that led to Clinton's impeachment by the House. He was later acquitted by the Senate. 

She said the relationship with Clinton was "consensual" but added that her boss "took advantage."

She wrote a revealing article in June about the humiliation that she endured following the scandalous affair with President Clinton. "It was time to burn the beret and bury the blue dress," she wrote.

Most recently, Lewinsky was photographed at the Vanity Fair's annual post-Oscars party in Beverly Hills.