Conventionally, a leukocytosis exceeding 50,000 WBC/mm3 with a significant increase in early neutrophil precursors is referred to as a<unk> . The peripheral blood smear may show myelocytes, metamyelocytes, promyelocytes, and rarely myeloblasts; however, there is a mixture of early mature neutrophil precursors, in contrast to the immature forms typically seen in acute leukemia. Serum leukocyte alkaline phosphatase is normal or elevated in<unk> , but is depressed in chronic myelogenous leukemia. The bone marrow in a<unk> , if examined, may be hypercellular but is otherwise typically unremarkable.<unk> s are generally benign and are not dangerous in and of themselves, although they are often a response to a significant disease state (see Causes above). However,<unk> s can resemble more serious conditions such as chronic myelogenous leukemia (CML), which can present with identical findings on the peripheral blood smear. Historically, various clues including the leukocyte alkaline phosphatase score and the presence of basophilia were used to distinguish CML from a<unk> . However, at present the test of choice in adults to distinguish CML is an assay for the presence of the Philadelphia chromosome, either via cytogenetics and FISH, or via PCR for the BCR/ABL fusion gene. The LAP (Leukocyte Alkaline Phosphatase) score is high in reactive states but is low in CML. In cases where the diagnosis is uncertain, a qualified hematologist or oncologist should be consulted.
Leukemoid reaction
Mast cell leukemia
Lymphoid leukemia
AIDS-related lymphoma
Prolymphocytic leukemia
Mixed-phenotype acute leukemia
Acute myeloid leukemia
Chronic neutrophilic leukemia