an indolent (slow-growing) cancer in which too many immature lymphocytes (white blood cells) are found mostly in the blood and bone marrow. sometimes, in later stages of the disease, cancer cells are found in the lymph nodes and the disease is called small lymphocytic lymphoma. also called chronic lymphocytic leukemia.
出典:Wiktionary
CLL (countable かつ uncountable, 複数形 CLLs)