Monocytosis

Can be reactive or clonal.

Peripheral blood monocytosis can be reactive and is often seen in association with: viral infections, chronic infections/inflammatory conditions such as tuberculosis, brucellosis leishmaniasis, subacute bacterial endocarditis, sarcoidosis, and connective tissue disorders.

Viral infection associated with monocytosis is associated with the temporal relationship with a febrile prodrome, the absence of immature myeloid cells on blood smear, and associated reactive lymphocytosis.

Monocytosis is an early sign of bone marrow recovery following myelosuppression due to infections and medications, including chemotherapy.

Clonal monocytosis is often persistent and is associated with hematopoietic stem cell disorders such as CMML, juvenile myelomonocytic leukemia, primar myelofibrosis, acute myelogenous leukemia with monocytic differentiation.