Updated: 10/4/2016

Leukemia

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Introduction
  • The most common malignancy of childhood
  • Forms include
    • acute lymphocytic leukemia (ALL)
      • neoplastic proliferation of lymphocytes
    • actue myeloblastic leukemia (AML)
      • neoplastic proliferation of myeloblasts
    • chronic myelocytic leukemia (CML)
      • neoplastic mature myeloid cells (granulocytes)
    • chronic lymphocytic leukemia (CLL)
      • neoplastic proliferation of naive B cells
Classification
  • ALL
    • represents 80% of cases of leukemia
    • peak incidence of 4 years of age
    • causes dimeralization of bones, periostitis, and lytic lesions
    • positive TdT nuclear staining
    • T-ALL
      • proliferation of T-lymphocytes
      • presents in teenagers
    • B-ALL
      • proliferation of B-lymphocytes
      • 12;21 translocation most commonly seen in children
      • 9;22 translocation most commonly seen in adults
  • AML
    • most commonly seen in older adults (5th-6th decade)
    • marrow failure secondary to crowding out of normal hematopoeisis by neoplastic proliferation
    • myeloblasts with Auer rods 
    • Acute Promyelocytic Leukemia (APL)
      • caused by 15;17 translocation 
        • disrupts retinoic acid receptor (RAR) required for myeloblast maturation
    • Acute megakaryoblastic leukemia 
      • associated with Down syndrome 
        • younger than 5 years 
    • Acute monocytic leukemia 
      • infiltration of the gums
  • CML
    • onset usually in older adults (5th-6th decade)
    • 9;22 translocation 
      • known as the Philadelphia chromosome
      • results in a fusion tyrosine kinase with increased activity (bcr-abl)
      • increased levels of bcr-abl leads to ↑ cell division and inhibition of apoptosis
  • CLL
    • commonly seen in older adults (5th-6th decade)
    • insidious onset of symptoms
    • smudge cells on peripheral smear 
Presentation
  • Symptoms
    • recurrent infections
    • bleeding
    • fatigue
    • lymphadenopathy (more common in CLL)
  • Physical exam 
    • hepatosplenomegaly
      • secondary to leukemic infiltrate
    • lymphadenopathy
      • secondary to leukemic infiltrate
Treatment
  • Nonoperative
    • chemotherapy
      • T-ALL & B-ALL
      • may predispose to pathologic fractures
      • all-trans-retinoic acid for APL (AML subtype)
      • imatinib for CML
 

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