Chilblains are a common problem in the colder climates. They start as painful and itchy red lesions, mostly on the toes and progress to a darker bluish colour as they become chronic.
There was a detailed discussion of chilblains in this episode of PodChatLive:
Chilblains are typically treated by preventing them in the first place, using creams to stimulate the circulation, protecting the skin from breaking down and keeping the feet warm with hosiery and shoes.
All the latest research in chilblains is listed on Podiatry Arena.