on 7.2.09 with 0 comments

  • Mostly in kids and young adults; 80% of childhood leukemia

  • Almost twice as common in whites and more common in boys

  • Lymphadenopathy (from leukemic infiltration), hepatosplenomegaly (also leukemic infiltration), and infiltration of other organs (especially the brain and testicles) is common

  • May have a mediastinal mass reflecting thymic involvement with T cell ALL

  • Morphologic classification (FAB)

    • ALL L1

      • Homogenous population of small lymphoblasts (lymphoblasts = precursor B or T cells) with scant cytoplasm and variable basophilia

      • Nuclei are round and clefted with homogenous chromatin; inconspicuous or absent nucleoli

      • 85% of all childhood ALL

      • Often have PAS “block” positivity

    • ALL L2

      • Heterogeneously sized population of relatively large lymphoblasts with moderately abundant cytoplasm and variable basophilia

      • Multiply cleaved nuclei with prominent nucleoli and clumped chromatin

      • 15% of childhood ALL; most frequent adult ALL

      • PAS

    • ALL L3

      • Homogenous population of intermediate sized cells (L1 <>

      • Cytoplasm is abundant, deeply basophilic, and vacuolated (vacuoles are oil red O (+))

      • Nuclei are round to oval with 1+ prominent nucleoli

      • This is a leukemic manifestation of Burkitt’s lymphoma

        • If it’s first and most prominently manifested in the blood it’s leukemia

        • If it’s first and most prominently manifested in the nodes it’s lymphoma

      • 1-2% of childhood ALL

  • Immunologic classification

    • 80% are of B cell origin; those that are of T cell origin are arrested in the early intrathymic stages

    • Prognosis related to immunophenotype

      • Best with early precursor B cell ALL

      • Intermediate with immature T cell and pre-B cell ALL

      • Poorest with mature B cell ALL (ALL L3; leukemic Burkitt’s)

      • ALL in kids 2-10 YOA with early pre-B phenotype and hyperdiploidy carries the best prognosis

      • Adults (no matter phenotype) and kids with mature B phenotype have a very poor prognosis

Category: Medical Subject Notes , Pathology Notes



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