Chronic myelomonocytic leukaemia or, in the US, chronic myelomonocytic leukemia, abbreviated to CMML, is a rare form of blood cancer. It happens when there are too many monocytes, a type of white blood cell in the blood - see <a href="https://www.cancerresearchuk.org/about-cancer/other-conditions/chronic-myelomonocytic-leukaemia-cmml/about" target="_blank" rel="noopener">here</a> for more information