Acute undifferentiated leukemia is a very rare type of aggressive leukemia — a type of cancer. It’s a very serious condition because researchers don’t know much about it. Leukemia is a type of cancer ...

Chronic lymphocytic leukemia (CLL) and prolymphocytic leukemia (PLL) are types of blood cancer. They develop in types of white blood cells called B cells or T cells, or the precursors to these cells.