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April, 2026
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Chokri Ben Lamine: Differentiating Reactive from Clonal Causes in Adult Neutrophilia
Apr 1, 2026, 17:15

Chokri Ben Lamine: Differentiating Reactive from Clonal Causes in Adult Neutrophilia

Chokri Ben Lamine, Adult Hematology and SCT Assistant Consultant at Oncology Center of Excellence at King Faisal Specialist Hospital and Research Center, shared a post on X:

Neutrophilia approach: ANC greater than 7.5 ×10⁹/L (adult) should be classified reactive vs clonal

Step 1: confirm

  • repeat CBC with differential
  • review smear (toxic granulation? left shift? blasts?)

Step 2: severity and pattern

  • mild (<15) | moderate (15–30) | severe (>30) | extreme (>50 = leukemoid?)
  • acute vs chronic

Reactive causes (most common)

  • infection (bacterial, severe viral early)
  • inflammation (RA, IBD, vasculitis)
  • stress (trauma, surgery, MI)
  • drugs (steroids, G-CSF, lithium)
  • smoking, obesity
  • asplenia/post-splenectomy

Clonal / hematologic

  • MPN: CML, PV, ET, MF
  • CNL (rare, CSF3R+)
  • AML with leukocytosis
  • MDS/MPN overlap

Smear clues

  • toxic granulation/Döhle bodies indicates a reactive
  • basophilia with myelocyte bulge then think CML
  • blasts raise concern for acute leukemia

Step 3: basic workup

  • CRP/ESR
  • cultures ± imaging if infection suspected
  • medication review

Step 4: rule out CML early
BCR-ABL1 PCR (must not miss)

If persistent/unexplained

  • JAK2 / CALR / MPL
  • CSF3R if CNL suspected
  • bone marrow biopsy

Red flags (urgent)

  • WBC  greater than 50–100
  • blasts on smear
  • organomegaly
  • constitutional symptoms

Pearls

  • neutrophilia with basophilia should be considered CML until proven otherwise
  • steroid-induced neutrophilia results from demargination (no left shift)
  • leukemoid reaction can mimic leukemia but LAP high

One-liner
most neutrophilia is reactive, but always exclude CML first”

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