Features of a Leukoerythroblastic Reaction

The leukoerytoblastic reaction (LEBR) refers to the presence of immature erythroid and myeloid precursors in the peripheral blood.

Findings in the peripheral blood:

(1) normoblasts

(2) immature neutrophils with occasional blasts

(3) usually anemia with polychromasia

Conditions Associated with LEBR	Other Findings on the Blood Smear	Other Findings
metastatic carcinoma (including myelophthisis)		older patient with history of cancer (breast, prostate, lung); bone pain; X-ray changes
malignant lymphoma, Hodgkin's disease		lymphadenopathy, splenomegaly
myeloproliferative syndrome, including myelofibrosis	teardrop red cells in myelofibrosis	splenomegaly
myelodysplasia	dysplasia in erythroid, megakaryocytoid and myeloid series, including cytoplasmic fragments from megakaryocytes
acute leukemia	> 5% blasts
multiple myeloma	rouleaux	elevated total protein, monoclonal protein
acute anemia (hemorrhage, hemolysis)		clinical history, possible positive direct antiglobulin test
megaloblastic anemia	megaloblasts with high MCV	low serum folate or vitamin B12
thalassemia major	microcytic anemia, target cells	family history
Gaucher's disease		young patient with hepatosplenomegaly
osteopetrosis		X-ray changes
renal osteodystrophy		renal failure; hyper-parathyroidism
Paget's disease of bone		elevated serum alkaline phosphatase; X-ray changes
tuberculosis		positive PPD, chest X-ray changes
congenital syphilis		positive serology and stigmata
radiation		radiation exposure
benzene poisoning		chemical exposure

Differential diagnosis:

(1) Neupogen therapy (granulocyte colony stimulating factor)

(2) acute infection with a "left shift" (metamyelocytes, myelocytes)

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