If untreated, the disease progresses slowly to the bones, abdominal organs, and uninvolved skin. But diagnosed early, the disease can be adequately treated and is rarely fatal. Treatment is potassium iodine taken orally several times a day for up to three months. Expect upset stomachs. I believe there is another treatment that has been developed which is preferred over this.
Newer information indicates some uncertainty as to the fungal species.
An advanced case I was one of the lucky people to get this disease, two years ago. The wound on the back of my hand widened and opened, and was ugly and refused to heal. It didn't hurt really, just looked awful. I had to add it to water and drink it three times a day. Pain in the neck, and it tastes icky.