Leukemia is classified by two things: the kind of white blood cells affected and the pace at which the disease progresses. In terms of the disease’s progress rate, it can be classified either as acute or as chronic. Acute leukemia progresses very quickly, leading to the accumulation of harmful cells in the bone marrow. Chronic leukemia, on the other hand, progresses at a slow pace. This article studies the most common and rare types of leukemia.

• Acute lymphocytic leukemia (ALL)
  This type of leukemia progresses rapidly. In this, the white blood cells in the bone marrow multiply at an uncontrollable rate, quickly replacing healthy cells. The leukemia cells are transmitted into the bloodstream from where they reach other healthy organs and tissues, including the liver, brain, lymph nodes, and testes. They settle in these organs and further continue to grow and divide. The fast growth, division, and spread of these leukemia cells can lead to many possible symptoms.
• Chronic lymphocytic leukemia (CLL)
  This is slow-progressing cancer that originates in the bone marrow’s lymphocytes and is transmitted into the bloodstream. It may also spread to the nearby lymph nodes and other body organs such as the spleen and the liver. This type of leukemia develops when too many impaired lymphocytes accumulate in the body, crowding out the normal cells and making it difficult for the body to fight infections.
• Acute myeloid leukemia (AML)
  In this, leukemia may begin in the blood cells other than the lymphocytes. It may also originate in the red blood cells and platelets. It is a quick-developing form of cancer of the bone marrow and blood.
• Chronic myeloid leukemia (CML)
  This type of leukemia is also known as myelogenous leukemia, in which the cells other than the lymphocytes in the bone become impaired. Over time, these damaged cells spread to the bloodstream and, eventually, to other parts of the body.
• Hairy cell leukemia (HCL)
  The discussion of the most common and rare types of leukemia is not complete without talking about this one. This is a rare sub-category of CLL that progresses slowly. This occurs when the bone marrow produces too many lymphocytes i.e., white blood cells that fight infection. As the number of lymphocytes increases, a lesser number of white and red blood cells and platelets are produced.
• Myelodysplastic syndromes (MDS)
  This disease refers to changes in the bone marrow and blood cells. The bone marrow starts producing very little red blood cells, white blood cells, and platelets, leading to many potential symptoms.

These are some of the most common and rare types of leukemia. In case you feel you have any symptoms of this disease, you must immediately consult your doctor.