Leukemoid reaction




Leukemoid reaction

Hematological system


Iron deficiency anemia



Sideroblastic anemia

Anemia of chronic disease

Lead poisoning

Hemolytic disease of the newborn

Glucose-6-phosphate dehydrogenase (G6PD) deficiency

Autoimmune hemolytic anemia

Pyruvate kinase deficiency

Paroxysmal nocturnal hemoglobinuria

Sickle cell disease (NORD)

Hereditary spherocytosis

Anemia of chronic disease

Aplastic anemia

Fanconi anemia

Megaloblastic anemia

Folate (Vitamin B9) deficiency

Vitamin B12 deficiency

Fanconi anemia

Diamond-Blackfan anemia

Heme synthesis disorders

Acute intermittent porphyria

Porphyria cutanea tarda

Lead poisoning

Coagulation disorders


Vitamin K deficiency

Platelet disorders

Bernard-Soulier syndrome

Glanzmann's thrombasthenia

Hemolytic-uremic syndrome

Immune thrombocytopenic purpura

Thrombotic thrombocytopenic purpura

Mixed platelet and coagulation disorders

Von Willebrand disease

Disseminated intravascular coagulation

Heparin-induced thrombocytopenia

Thrombosis syndromes (hypercoagulability)

Antithrombin III deficiency

Factor V Leiden

Protein C deficiency

Protein S deficiency

Antiphospholipid syndrome


Hodgkin lymphoma

Non-Hodgkin lymphoma


Chronic leukemia

Acute leukemia

Leukemoid reaction

Leukemoid reaction

Dysplastic and proliferative disorders

Myelodysplastic syndromes

Polycythemia vera (NORD)

Myelofibrosis (NORD)

Essential thrombocythemia (NORD)

Langerhans cell histiocytosis

Mastocytosis (NORD)

Plasma cell dyscrasias

Multiple myeloma

Monoclonal gammopathy of undetermined significance

Waldenstrom macroglobulinemia

Hematological system pathology review

Microcytic anemia: Pathology review

Non-hemolytic normocytic anemia: Pathology review

Intrinsic hemolytic normocytic anemia: Pathology review

Extrinsic hemolytic normocytic anemia: Pathology review

Macrocytic anemia: Pathology review

Heme synthesis disorders: Pathology review

Coagulation disorders: Pathology review

Platelet disorders: Pathology review

Mixed platelet and coagulation disorders: Pathology review

Thrombosis syndromes (hypercoagulability): Pathology review

Lymphomas: Pathology review

Leukemias: Pathology review

Plasma cell disorders: Pathology review

Myeloproliferative disorders: Pathology review


Leukemoid reaction


0 / 8 complete

USMLE® Step 1 questions

0 / 1 complete

High Yield Notes

10 pages


Leukemoid reaction

of complete


USMLE® Step 1 style questions USMLE

of complete

A 47-year-old man comes to the office due to 2 days of sore throat, purulent nasal discharge and facial pain. Past medical history is significant for several sinus infections over the past 6 months, all of which resolved with oral antibiotics. Temperature is 38.5°C (101.4°F), pulse is 80/minute, respirations are 19/minute, and blood pressure is 130/70 mmHg. Physical examination shows pharyngeal erythema and maxillary sinus tenderness. There is no lymphadenopathy. Laboratory results are as follows:    
Laboratory value  Result
Complete blood count 
Hemoglobin   10 g/dL 
 Platelets   600,000/mm3 
 Leukocytes   100,100/mm3 
 Neutrophils  40% 
 Myelocytes  32% 
 Metamyelocytes  10% 
 Band forms  1% 
 Blast cells  1% 
 Lymphocytes  7% 
Fluorescence in situ hybridization (FISH) analysis reveals a bcr-abl fusion gene. Which of the following additional findings is most likely to be seen in this patient?

Memory Anchors and Partner Content

External References

First Aid







Leukemoid reaction p. 211

External Links


Leukemoid reaction refers to an increase in white blood cell count, specifically above 50,000 cells/mm �, due to causes other than leukemia. Leukemoid reactions can occur as a response to stress or infection, and can mimic symptoms of leukemia, such as fatigue, weight loss, and bruising. Distinction between the two needs lab tests, which show elevated neutrophils (suggestive of an acute inflammatory process) in case of leukemoid reaction, and the absence of dysplastic cells (seen in leukemia).


Copyright © 2023 Elsevier, except certain content provided by third parties

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.