leukemoid reaction

Etiology

• infectious disease caused by bacteria or viruses
  • tuberculosis
  • diptheria
  • chickenpox
  • Clostridium difficile most common nosocomial cause
• eclampsia
• burns
• toxic agents
• malignant neoplasms
  • carcinoma of the colon
  • carcinoma of the lung
  • carcinoma of the kidney
• acute hemorrhage or hemolysis
• glucocorticoids
• G-CSF therapy
• cardiac arrest
• hepatorenal syndrome

Pathology

• a moderate, advanced or sometimes extreme degree of leukocytosis in blood, similar to that occurring in various forms of leukemia, but not the result of leukemic disease
• generally, there is a disproportionate increase in one of the forms of leukocytes (including immature stages)
• examples of myelocytic, lymphocytic, monocytic or plasmocytic leukemoid reactions may be indistinguishable from leukemias

Laboratory

• complete blood count
  • leukocytosis, WBC count < 45,000/uL; > 50,000/uL (MKSAP19)

Differential diagnosis

• leukemia, especially chronic myeloid leukemia
  • if WBC count is > 45,000/mm3, the most likely cause is leukemia
  • if WBC < 45,000/mm3, infection is the most likely etiology

More general terms

• myeloproliferative disorder
• leukocytosis