NK Cell Leukemia (aka Aggressive NK Cell Leukemia, ANKL)

Epidemiology

  • Incidence
    • Rare: only 150 cases have been reported in the literature
    • Accounts for <0.1% of all lymphoid neoplasms
  • Sex: approximately M=F
  • Median Age of Onset: 40’s
  • Race: occur mostly in non-Caucasians
  • Association with Epstein-Barr Virus (see Epstein-Barr Virus)

Physiology

  • Probable Derivation from Stage 5 NK Cells in Peripheral Blood
    • This is distinct from Extranodal NK/T-Cell Lymphoma, Nasal Type (ENKL) (see Extranodal NK, T-Cell Lymphoma, Nasal Type), which is believed to be derived from stage 4 NK cells in secondary lymphoid tissue
    • These two diseases share a poor responsiveness to chemotherapy and poor prognosis
  • Expression of the MDR1 Gene Product, P-Glycoprotein, on Tumor Cell Surface: P-glycoprotein actively exports many anti-tumor drugs out of the tumor cell (vincristine and doxorubicin are exported, but methotrexate and L-asparaginase are not)
    • Confers resistance to typical antracycline-containing lymphoma regimens

Diagnosis

  • CD16 Expression: 70-80%

Clinical Sites of Involvement


Treatment

  • Poor Chemoresponsivness: 19% complete response rate
  • Patients in Good Condition: SMILE (Steroids + Methorexate + Ifosfamide + L-Asparaginase + Etoposide)
    • Should be dose-adjusted
  • Patients in Good Condition: L-Asparaginase + Dexamethasone, Then SMILE

Prognosis

  • Median Survival: 2 months

References

  • Treatment of Advanced Extranodal NK/T-Cell Lymphoma, Nasal Type and Aggressive NK Cell Leukemia. Int J Hematol 2010; 92: 697-701 [MEDLINE]