What is the most common type of leukemia that features "smudge cells"?

The presence of "smudge cells" is characteristically associated with chronic lymphocytic leukemia (CLL). Smudge cells are fragile, mature lymphocytes that rupture during the preparation of blood smears, leading to these distinctive appearances. This finding is often noted in cases of CLL due to the high lymphocyte count and the fragility of these cells, making it a classic laboratory finding in this type of leukemia.

Chronic lymphocytic leukemia is primarily characterized by a proliferation of mature B lymphocytes, which can lead to an accumulation of these cells in the blood, resulting in their fragility. The smudge cells are not typically observed in other types of leukemia like chronic myelogenous leukemia, acute lymphoblastic leukemia, or acute myeloid leukemia, which have different cellular characteristics and do not demonstrate this specific finding in the same way. Thus, the identification of smudge cells in a patient’s peripheral blood smear is a key diagnostic clue for chronic lymphocytic leukemia.