Chapter 12: Anemia Resulting from Marrow Infiltration

DEFINITIONS

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

• Leukoerythroblastosis refers to anemia with schistocytes, teardrop-shaped red cells, nucleated red cells, megakaryocytic fragments, and immature myeloid cells (e.g., neutrophilic myelocytes) in the blood.

ETIOLOGY AND PATHOGENESIS

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

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

• In most cases, the infiltration 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 (e.g., cytokines) or injury to the marrow microenvironment.

CLINICAL FEATURES

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

LABORATORY FEATURES

• 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 may rarely 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.

DIFFERENTIAL DIAGNOSIS

• Nucleated red cells and leukocytosis can be seen in overwhelming sepsis, primary myelofibrosis acute severe hypoxia (e.g., acute congestive heart failure), thalassemia major, and severe hemolytic anemia.

• Primary myelofibrosis (see Chap. 48) may be confused with metastatic disease with focal fibrosis.

• In the absence of a known primary site of cancer, it is important to rule out sarcoma of bone.

TREATMENT AND PROGNOSIS

• The goal of treatment is ...