Monocytosis often occurs during
chronic inflammation. Diseases that produce such a chronic inflammatory state: • Infections:
tuberculosis,
brucellosis,
listeriosis,
subacute bacterial endocarditis,
syphilis, and other viral infections and many
protozoal and
rickettsial infections (e.g.
kala azar,
malaria,
Rocky Mountain spotted fever). • Blood and immune causes: chronic
neutropenia and
myeloproliferative disorders. •
Autoimmune diseases, immune diseases and
vasculitis:
systemic lupus erythematosus,
rheumatoid arthritis and
inflammatory bowel disease. Monocytosis can be a symptom of
mast cell activation syndrome (MCAS). • Malignancies:
Hodgkin's disease and certain
leukaemias, such as
chronic myelomonocytic leukaemia (CMML) and
monocytic leukemia. • Recovery phase of neutropenia or an acute infection. • Obesity (cf. Nagareddy et al. (2014), Cell Metabolism, Vol. 19, pp 821–835) • Miscellaneous causes:
sarcoidosis, drug overdose,
lipid storage disease and ZNFX1 deficiency. During these stages of extreme inflammation, monocytosis can damage tissues because it increases the activation of the immune response and prevents the inflammation from subsiding which is seen in cases where sepsis occurs. ==Diagnosis==