From the Guidelines
Elevated monocytes on a complete blood count (CBC) should prompt further investigation to determine the underlying cause, as this condition can be associated with various diseases, including chronic infections, inflammatory disorders, and certain cancers, as noted in the study by 1. The presence of elevated monocytes, defined as a monocyte count exceeding 1x10^9/L, can be a diagnostic criterion for chronic myelomonocytic leukemia (CMML), a type of blood cancer, according to the study published in Haematologica by 1. Some key points to consider when evaluating elevated monocytes include:
- The comprehensive diagnostic criteria for CMML, which include blood monocytes > 1x10^9/L, bone marrow blasts <20%, and associated dysplasia in erythroid, granulocytic, or megakaryocytic lineages, as outlined in the study by 1.
- The importance of distinguishing between "dysplastic" and "proliferative" variants of CMML, considering a white blood cell (WBC) count of 13x10^9/L as a cut-off point, as discussed in the study by 1.
- The need to investigate other potential causes of monocytosis, such as chronic infections, inflammatory disorders, and autoimmune diseases, as elevated monocytes can be a marker of inflammation, as noted in the study by 1. Treatment should target the underlying cause of the elevated monocytes, rather than the elevated monocytes themselves, and may involve further testing, including blood work, imaging studies, or specialist referrals, as emphasized in the context of real-life clinical medicine. In terms of prognosis and risk classification, the study by 1 highlights the importance of considering factors such as the presence of blasts, dysplasia, and cytogenetic abnormalities in determining the risk of transformation to acute myeloid leukemia (AML) and overall survival. Overall, elevated monocytes on a CBC require careful evaluation and investigation to determine the underlying cause and develop an appropriate treatment plan, prioritizing morbidity, mortality, and quality of life as the primary outcomes, as guided by the most recent and highest-quality study by 1.
From the Research
Elevated Monocytes on CBC
Elevated monocytes on a complete blood count (CBC) can be an indication of various conditions, including neoplastic and non-neoplastic diseases.
- Monocytosis is a frequently encountered clinical condition that requires appropriate investigation due to its broad range of differential diagnoses 2.
- The adequate evaluation of monocytosis involves the integration of laboratory data, morphology, clinical findings, and the judicious use of ancillary studies 3.
Causes of Monocytosis
Monocytosis can be caused by a wide variety of conditions, including:
- Chronic myelomonocytic leukemia (CMML), a prototypical neoplasm with monocytosis 2, 4
- Other haematological malignancies 4
- Reactive or neoplastic causes 2
- Corticosteroid administration, although the mechanism is less clear 5
Diagnostic Approach
A stepwise diagnostic approach is recommended for patients presenting with monocytosis, including:
- Basic studies to highlight the phenotypic and functional heterogeneity in the monocyte compartment 2
- Flow cytometry studies to distinguish CMML from other reactive or neoplastic causes 2
- Integration of laboratory data, morphology, clinical findings, and ancillary studies 3
Clinical Significance
Monocytosis is associated with an increased risk of haematological malignancy, particularly CMML 4.