Differentials
Organ-specific or systemic infection (bacterial, fungal, viral)
SIGNS / SYMPTOMS
Presents outside the context of immunosuppression and neutropenia.
INVESTIGATIONS
Gram stain or cultures of body fluids or bone marrow may grow relevant organisms.
Imaging studies, where indicated, may identify source of infection.
Skin testing may indicate tuberculosis.
Leukocyte alkaline phosphatase is high in infection, whereas it is low in chronic myeloid leukemia.
Philadelphia chromosome (breakpoint cluster region-Abelson [BCR::ABL1] rearrangement) is absent.
<20% blasts in peripheral blood and bone marrow.
Leukemoid reaction
SIGNS / SYMPTOMS
Underlying cause of leukemoid reaction (i.e., corticosteroid use, infection, inflammatory disease, stress reaction) may be identified clinically.
INVESTIGATIONS
Leukocyte alkaline phosphatase is high in infection, whereas it is low in chronic myeloid leukemia.
<20% blasts in peripheral blood and bone marrow.
Essential thrombocythemia
SIGNS / SYMPTOMS
More indolent clinical course.
Symptoms and signs are nonspecific and may not differ from those of blast crisis.
Although blast crisis usually presents with low platelet counts, it can occasionally present with thrombocytosis.
INVESTIGATIONS
Presence of JAK2, CALR, or MPL mutations.
Bone marrow examination shows no blasts, with increased megakaryocytes.
No white blood cell or red blood cell abnormalities.
Philadelphia chromosome (BCR::ABL1 rearrangement) is absent.
<20% blasts in peripheral blood and bone marrow.
Atypical chronic myeloid leukemia, Philadelphia chromosome-negative
SIGNS / SYMPTOMS
Symptoms and signs are nonspecific and may not differ from those of blast crisis.
INVESTIGATIONS
Philadelphia chromosome (BCR::ABL1 rearrangement) is absent.
<20% blasts in peripheral blood and bone marrow.
Chronic myelomonocytic leukemia
SIGNS / SYMPTOMS
Symptoms and signs are nonspecific and may not differ from those of blast crisis.
INVESTIGATIONS
Philadelphia chromosome (BCR::ABL1 rearrangement) is absent.
<20% blasts in peripheral blood and bone marrow.
Persistent monocytosis (defined as absolute monocyte count ≥1 × 10⁹/L [≥1000/microliter] for at least 3 months).
Philadelphia-positive acute lymphoblastic leukemia
SIGNS / SYMPTOMS
Symptoms and signs are nonspecific and may not differ from those of blast crisis.
INVESTIGATIONS
Difficult to distinguish from blast phase of chronic myeloid leukemia.
Additional cytogenetic abnormalities may be present.
Philadelphia-positive acute myeloid leukemia
SIGNS / SYMPTOMS
Symptoms and signs are nonspecific and may not differ from those of blast crisis.
INVESTIGATIONS
Difficult to distinguish from blast phase of chronic myeloid leukemia.
Splenomegaly and peripheral basophilia less likely.[38]
Additional cytogenetic abnormalities are usually present.
Benign neutrophilic leukocytosis
SIGNS / SYMPTOMS
Symptoms and signs are nonspecific and may not differ from those of blast crisis.
INVESTIGATIONS
Philadelphia chromosome (BCR::ABL1 rearrangement) is absent.
<20% blasts in peripheral blood and bone marrow.
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