Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (331 page)

   Tissue necrosis (gangrene, mesenteric vein thrombosis)

   Therapy with granulocyte colony–stimulating factor (G-CSF) or granulocyte monocyte colony–stimulating factor (GM-CSF)

   Metastatic infiltration of the marrow

   
ACUTE LEUKEMIAS
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B LYMPHOBLASTIC LEUKEMIA/LYMPHOMA (B-ALL)

   Definition

B-ALL is a clonal disease affecting the lymphocytic B line, with heavy infiltration of bone marrow and peripheral blood. If the neoplasm is confined to a mass with no or minimal evidence of peripheral blood or bone marrow involvement, the term B lymphoblastic lymphoma is appropriate. With modern therapy, B-ALL has a good prognosis in children, but not in adults. To what this difference is attributable is not yet clear.

   Who Should Be Suspected?

   B-ALL is the most common form of cancer in childhood, comprising >85% of leukemias in children. The disease can however occur at any age. Children (peak incidence at age 2–3 years) or adults older than 65, presenting with acute onset of fever, infection, bleeding, fatigue, musculoskeletal pain (particularly in adolescents), and characteristic findings on the CBC. Lymphadenopathy and hepatosplenomegaly are present in the majority of patients but are not massive.

   Predisposing factors: children with certain genetic disorders such as Down syndrome, neurofibromatosis type 1, Bloom syndrome, and ataxia telangiectasia.

   Poor prognostic signs at presentation: WBC count >100,000/μL, platelet count <50,000/μL, CD10 negativity, certain karyotypic abnormalities, occurrence of the disease before age 1 (probably having occurred before birth) or after age 10, and induction failure. Mature B leukemic phenotype rather than the precursor B cell is associated with poorer prognosis.

   Laboratory Findings

Laboratory diagnosis is based on morphology, immunophenotype, and cytogenetic/genetic analysis.

Morphology

   Blood: CBC

   Anemia, moderate to severe.