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



dysplasia in erythroid, megakaryocytoid and myeloid series, including cytoplasmic fragments from megakaryocytes


acute leukemia

> 5% blasts


multiple myeloma


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



X-ray changes

renal osteodystrophy


renal failure; hyper-parathyroidism

Paget's disease of bone


elevated serum alkaline phosphatase; X-ray changes



positive PPD, chest X-ray changes

congenital syphilis


positive serology and stigmata



radiation exposure

benzene poisoning


chemical exposure


Differential diagnosis:

(1) Neupogen therapy (granulocyte colony stimulating factor)

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


To read more or access our algorithms and calculators, please log in or register.