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DEFINITIONS

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  • Anemia or pancytopenia associated with extensive marrow infiltration is called myelophthisic anemia.

  • Leukoerythroblastosis refers to the presence of nucleated red cells, and myeloid precursor cells (eg, neutrophilic myelocytes) in the blood. These finding may be accompanied by schistocytes, teardrop-shaped red cells, and megakaryocytic fragments in patients with myelophthisic anemia.

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ETIOLOGY AND PATHOGENESIS

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  • Table 12–1 lists the conditions that cause marrow infiltration.

  • Invasion of blood vessels is the essential component of cancer cell metastasis and often involves the loss of E-cadherin.

  • In most cases, the marrow infiltration of metastatic cells is focal, with surrounding areas of normal or hyperactive marrow.

  • Disruption of the microenvironment by infiltration with foreign cells leads to premature release of immature blood cells from the marrow.

  • Myelophthisic anemia is most often caused by humoral factors (eg, cytokines) and injury to the marrow microenvironment.

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Table Graphic Jump Location
TABLE 12–1CAUSES OF MARROW INFILTRATION
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CLINICAL FEATURES

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  • The clinical features of marrow infiltrative disorders are usually those of the underlying disease, but the marrow replacement may also accentuate associated cytopenias.

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LABORATORY FEATURES

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  • Anemia is mild to moderate.

  • Leukocyte and platelet counts may be high or low depending on the nature and extent of marrow replacement.

  • Blood film may show anisocytosis and poikilocytosis, with schistocytes, teardrop cells, nucleated red cells, immature granulocytic cells, and megakaryocytic fragments.

  • Leukocyte alkaline phosphatase activity is normal or increased.

  • Clusters of cancer cells rarely may be found on the blood film (carcinocythemia).

  • Marrow biopsy is the most reliable diagnostic procedure. Marrow aspiration may also be of value. Aspiration or biopsy is more likely to be positive if taken from a tender area of bone.

  • Sites of marrow infiltration may be detected by technetium-99m sestamibi uptake, magnetic resonance imaging, or fluorine-18 fluorodeoxyglucose with positron emission tomography.

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DIFFERENTIAL DIAGNOSIS

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  • Nucleated red cells and leukocytosis can be seen in overwhelming sepsis, primary myelofibrosis, acute severe hypoxia ...

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