'Grey's' prognosis: Spinoff?

LOS ANGELES (AP) — The prognosis is uncertain, but ABC's hit medical drama "Grey's Anatomy" might turn out to have spin-off syndrome.

A special two-hour episode, featuring cast member Kate Walsh and guest starring Taye Diggs, is a test run for a possible new series, ABC said.

The premise is being developed and the episode will air sometime this season, the network said.

Walsh plays neonatal surgeon Addison Shepherd, part of the romantic triangle involving Dr. Derek Shepherd (Patrick Dempsey) and intern Meredith Grey (Ellen Pompeo). Extracting Walsh's character from the series could prove tricky for series creator Shonda Rhimes.

Although comedy spin-offs once were common ("Cheers" begat "Frasier," "All in the Family" begat "Maude" and "The Jeffersons"), it's a rare occurrence among dramas. CBS made it work for "Knots Landing," which pulled characters from the hit "Dallas" and earned a 14-year run.

"Grey's Anatomy" has been a key player for Walt Disney Co.-owned ABC and has prospered in a move from Sunday to Thursday night, drawing up to 25 million-plus viewers in its third season.

In recent months, the series drew as much attention for its cast conflicts as plot twists. Isaiah Washington, who plays Dr. Preston Burke, publicly apologized for using an anti-gay slur about co-star T.R. Knight and sought counseling.