Actress Valerie Harper diagnosed with rare form of brain cancer – Elizabeth Cohen breaks it down

Actress Valerie Harper, best known for her days on the hit shows "Rhoda" and The Mary Tyler Moore Show has been diagnosed with a rare form of cancer called that's affecting her brain. CNN Senior Medical Correspondent Elizabeth Cohen explains exactly what her rare condition is and what Harper is facing.

“This is not a tumor,” Cohen says. Loose cells in Harper’s spinal fluid are affecting her meninges, or the covering over the brain. "There are not a lot of great treatments for this," Cohen says.

CNN is told Harper is receiving chemotherapy. Doctors say "chemotherapy in this case, isn't really done to prolong life," but will help control pain and seizures for the time being, Cohen says. It may prolong life by a few weeks, but not by a lot. “She was told by her doctors [she has] about three months,” Cohen says. “It’s really a terrible, terrible form of cancer.”

Meanwhile, Harper is staying strong, appearing on talk shows to raise awareness about her illness with some inspiring words.