Relapsed hairy cell leukemia has come back after treatment. Refractory hairy cell leukemia has not responded to treatment.

Glossary Terms

A rare type of leukemia in which abnormal B-lymphocytes (a type of white blood cell) are present in the bone marrow, spleen, and peripheral blood. When viewed under a microscope, these cells appear to be covered with tiny hair-like projections.

Cancer that does not respond to treatment. The cancer may be resistant at the beginning of treatment or it may become resistant during treatment. Also called resistant cancer.

The return of signs and symptoms of cancer after a period of improvement.