Primary diagnosis: Chronic Myeloid Leukemia (CML) until proven otherwise.
Why CML?
The combination of:
Massive splenomegaly
Marked leukocytosis (WBC >137,000/µL)
Severe anemia (Hb 6.3 g/dL)
Peripheral smear showing a full spectrum of myeloid maturation (myelocytes, metamyelocytes, bands, neutrophils)
Basophilia
is highly characteristic of chronic-phase CML.
Crucial next step
✅ Confirm BCR-ABL1 fusion (Philadelphia chromosome)
Tests:
Quantitative PCR for BCR-ABL1 (preferred)
FISH for BCR-ABL1
Cytogenetics demonstrating t(9;22)(q34;q11)
Additional workup
Bone marrow aspiration/biopsy
Differential count with blast percentage
Baseline uric acid, LDH, renal function
Risk stratification (Sokal/ELTS score)
Management after confirmation
Start a tyrosine kinase inhibitor (TKI) such as:
Imatinib
Dasatinib
Nilotinib
If symptomatic hyperleukocytosis is present, supportive measures (hydration, cytoreduction) may be needed while awaiting confirmation.
Exam pearl
> Massive splenomegaly very high WBC basophilia all stages of myeloid precursors on peripheral smear = CML until proven otherwise.
The next diagnostic step is BCR-ABL1 testing (Philadelphia chromosome).