Thanks to Grace for presenting the case of a middle aged man who presented with chronic weight loss, acute SOB, and splenomegaly on exam, found to have a WBC of 188 on work up and chest imaging concerning for leukostasis.

Clinical Pearls

• Most common cause of splenomegaly is portal HTN.  But the ddx is broad (see schema below).
• Most common cause of a WBC 25k-75k is infection (C diff)
• WBC >100k is leukemia until proven otherwise.
• Leukostasis is symptomatic hyperleukocytosis, most commonly associated with AML.
• Management involves lowering the WBC by leukapharesis, hydrea, and TKIs (if CML) and preventing TLS.

Splenomegaly DDx

• ↑ Water: portal HTN (most common cause)
• ↑ Cells:
  • RBCs
    • Hemolysis ⇒ Thalassemias, hereditary spherocytosis, malaria, babesia
  • WBCs
    • Infection
      • Mono ⇒ EBV, CMV, HIV
      • Tick-borne ⇒ Rickettsia, anaplasmosis, ehrlichiosis
      • Granuloma ⇒ TB, histo, leishmaniasis
    • Autoimmune
      • Sarcoid
      • Still’s
      • Felty
    • Lymphoma
    • Myeloproliferative d/o
      • Polycythemia vera
      • Essential thrombocythemia
      • CML
• ↑ Molecules:
  • Amyloidosis
  • Other (lysosomal and glycogen storage diseases)

Leukostasis:

• Defined as symptomatic hyperleukocytosis and is a hematologic emergency!
• Mortality rate can be as high as 40% within the first week of presentation.
• Clinical manifestations of ischemia primarily in CNS, MI, lungs, and kidneys.  Can also see limb ischemia and priapism.
• Malignancies at highest risk of leukostasis in order of prevalence:
  • AML (WBC >50k)
  • ALL (WBC >100k, though tends to present with TLS and DIC much more commonly than leukostasis)
  • CML (WBC >100k), generally if in myeloid blast crisis
  • CLL (WBC >400k)
• Treatment:
  • FLUIDS, lots and lots of fluids
  • Cytoreduction: lowers the WBC
    • Leukapharesis: not readily available as it requires a dialysis line and trained nursing staff
    • Hydroxyurea: to lower the WBC
    • Tyrosine kinase inhibitors (especially for CML related leukostasis)
    • Induction chemo (for non-CML related leukostasis)
  • Prevent tumor lysis syndrome:
    • FLUIDS
    • Allopurinol
    • Uric acid lowering therapy
  • In hemodynamically stable patients AVOID TRANSFUSION – it’s like adding fuel to the fire and can worsen ischemia. Platelet transfusion is less dangerous than RBCs and you may have to do it before trialysis line placement.

TLS:

• ↑K, ↑Phos, ↑uric acid, ↑creatinine, ↓calcium
• Occurs in bulky or chemosensitive tumors with high proliferative rate (Burkitt’s lymphoma, acute leukemias, small cell lung cancer)
• Allopurinol takes 1-2 days to show effect and does not reduce preexisting elevated uric acid levels so use rasburicase if uric acid already high or preemptively if TLS risk is high or if there is kidney injury.
• HD if concern for renal damage

Causes of pseudohyperkalemia

• Technique of blood drawing (tourniquets and fist pumping)
• Thrombocytosis
• Leukocytosis (>120k)