Atypical Chronic Myeloid Leukemia, BCR-ABL1 Negative
Definition
- Neutrophilic leukemic disorder with myeloproliferative and myelodysplastic features but lacking specific cytogenetic abnormalities
Diagnostic Criteria
-
Peripheral blood leukocytosis must be >13 x 109/μL
- May be marked (>300 x 109/μL)
- Primarily due to neutrophils and neutrophilic precursors
- Promyelocytes, myelocytes and metamyelocytes usually make up 10-20% of WBC
- Monocytes must be <10% of WBC (may rarely slightly exceed 1 x 109/μL)
- Basophils usually <2% of WBC
- May be marked (>300 x 109/μL)
- Blasts <20% in blood and marrow
- Hypercellular bone marrow, predominantly granulocytic
- Erythrocytic and megakaryocytic hyperplasia may also be present
- Prominent granulocytic dysplasia must be present in blood and marrow
- Erythrocytic and megakaryocytic dysplasia may also be present
- Ph chromosome, BCR-ABL1, PDGFRA, PDGFRB, FGFR1 abnormalities and acute myeloid leukemia-defining translocations (e.g. inv(16), t(8;21)) must be absent
- Nonspecific karyotypic abnormalities and/or mutations are present in most cases
Myelodysplasia is defined by morphologic features of abnormal cellular maturation in at least one bone marrow lineage
- Not all features are applicable to all disorders
- Dyserythropoeisis
- Peripheral blood erythrocyte abnormalities
- Normocytic, normochromic anemia
- Macrocytosis
- Dimorphic red blood cells (RBC)
- Mixture of normal RBC and hypochromic microcytic RBC
- Often seen in Sideroblastic Anemia (RARS)
- Mixture of normal RBC and hypochromic microcytic RBC
- Basophilic stippling
- Poikilocytosis
- Varying shapes, frequently macro-ovalocytes
- Bone marrow erythroid lineage abnormalties
- Erythroid hyperplasia or hypoplasia
- Megaloblastoid / megaloblastic changes
- Dyssynchronous maturation of nucleus and cytoplasm of erythroid precursors
- Nucleus lags behind cytoplasm
- Dyssynchronous maturation of nucleus and cytoplasm of erythroid precursors
- Megaloblastoid / megaloblastic changes
- Ring sideroblasts
- ≥5 iron granules encircling ≥1/3 of the nucleus
- Usually either many or none
- Cytoplasmic vacuoles
- Also seen in copper deficiency
- Nuclear changes
- Multinuclearity
- Nuclear budding, hyperlobulation and satellite nuclei
- Internuclear bridging
- Erythroid hyperplasia or hypoplasia
- Peripheral blood erythrocyte abnormalities
- Dysgranulopoiesis
- Peripheral blood and/or bone marrow findings (easier seen in peripheral blood)
- Hypogranularity
- Pale cytoplasm almost indistinguishable from background on slide
- Nuclear hypolobation or irregular hypersegmentation (>5 lobes)
- Pseudo Pelger-Huet anomaly
- Two equal size nuclear lobes connected by a thin strand of chromatin
- Pseudo Pelger-Huet anomaly
- Infrequent findings
- Abnormal cytoplasmic granules (pseudo Chediak-Higashi granules)
- Giant grey to red granules
- Dohle bodies
- Small blue cytoplasmic inclusions
- Often found at periphery of cell
- Auer rods
- Rod-like structures formed by fusion of primary granules
- May be found in blasts or maturing granulocytes
- Abnormal cytoplasmic granules (pseudo Chediak-Higashi granules)
- Hypogranularity
- Peripheral blood and/or bone marrow findings (easier seen in peripheral blood)
- Dysmegakaryopoiesis
- Peripheral blood platelet abnormalities
- Giant
- Larger than a red blood cell
- Bizarre
- Irregular shapes and protrusions
- Hypogranularity
- Compare to normal platelets with purple granules
- Giant
- Bone marrow megakaryocyte abnormalities
- Micromegakaryocytes
- Smaller than a promyelocyte
- Nuclear hypolobation
- Prominent in 5q- syndrome
- A single lobe is typically seen in a small megakaryocyte
- Multinucleation
- Distinct nuclei without a connecting strand of chromatin
- Cytoplasmic hypogranularity
- Micromegakaryocytes
- Peripheral blood platelet abnormalities
Dita Gratzinger MD PhD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting: 11/6/11
