Extravasation of blood through a ruptured blood vessel wall
Vascular wall disturbances like
–Hypoxia, infections, drug, toxins
Other hemorrhagic diatheses
–Thrombocytopenia (low platelet count)
–Thrombasthenia (defective platelet function):
–Abnormalities in clotting factors.
A leukemoid reaction (LR) is a hematological disorder, defined by a leukocyte count greater than 50,000 cells/mcL with reactive causes outside the bone marrow
LR is characterized by a significant increase in mature neutrophils in the peripheral blood and a differential count showing left shift.
The diagnosis of LR is based on the exclusion of chronic myelogenous leukemia (CML) and chronic neutrophilic leukemia (CNL).
Acute bacterial infections, especially those caused by pyogenic organisms;
sterile inflammation caused by, for example, tissue necrosis (myocardial infarction, burns)
Allergic disorders such as asthma, hay fever
allergic skin diseases (e.g., pemphigus, dermatitis herpetiformis)
certain malignancies (e.g., Hodgkin disease and some non-Hodgkin lymphomas);
collagen vascular disorders and some vasculitides;
Rare, often indicative of a myeloproliferative disease (e.g., chronic myelogenous leukemia)
Chronic infections (e.g., tuberculosis), bacterial endocarditis, rickettsiosis and malaria;
collagen vascular diseases (e.g., systemic lupus erythematosus)
inflammatory bowel diseases (e.g., ulcerative colitis)
Accompanies monocytosis in many disorders associated with chronic immunologic stimulation (e.g., tuberculosis, brucellosis);
viral infections (e.g.,hepatitis A, cytomegalovirus, Epstein-Barr virus);
Bordetella pertussis infection.