A full-frontal, nude photo of a 20-year-old Madonna fetched $37,500 at auction Thursday, an apparent record auction price for a photograph of the superstar singer.

An unnamed European buyer bought the picture, which had been expected to sell for up to $15,000, according to Christie's auction house.

Madonna, then known as Madonna Louise Ciccone, was a dancer trying to make ends meet when she answered a newspaper ad seeking a nude model. She may have earned as little as $25 for the 1979 photo session.

WARNING: EXPLICIT MATERIAL. This nude photo of Madonna sold for $37,500.

Lee Friedlander's raw, explicit black-and-white image appeared in Playboy in 1985. Friedlander has said of the photo session that Madonna "seemed very confident, a street-wise girl. She told me she was putting a band together but half the kids that age are doing that. She was a good professional model."

The photograph auctioned Thursday was one of six from that shoot that appeared in Playboy; the other five pictures were sold together in 2003 for $7,170.

PHOTOS: Madonna's Many Transformations.

A Herb Ritts photo of Madonna's "True Blue" album cover, which sold for more than $15,000 in 2006, is the most expensive photograph of the singer to sell previously at auction, Christie's said.

Another photograph of Madonna, by Helmut Newton, sold Thursday for $18,750, beating a $15,000 estimate. In that shot, also sold to Playboy in the 1980s, Madonna sports lingerie, curly blond hair and a seductive expression. A man kneels beside her.

VIDEO: Click here for videos about Madonna.

The Madonna photos were among 150 images, by some of the biggest names in photography, auctioned from the collection of Leon and Michaela Constantiner. They feature fashion and other celebrity icons.

The sale fetched more than $900,000 in all, including a top price of $242,500 for "Sie Kommen," Newton's images of nude models for the Italian and French versions of Vogue in the 1980s.