ICSH Recommendations for Monocyte Cell Lineage Morphologic Identification, Nomenclature Harmonization, and...

Area of Science:

• Hematology
• Immunology
• Cell Biology

Background:

• Monocytes are crucial for immune responses, inflammation, and tissue repair within the Mononuclear Phagocyte System.
• Inconsistent nomenclature and morphology hinder accurate identification of monocyte lineage cells, impacting diagnosis of hematologic disorders.
• The rise of automated and AI-driven diagnostics necessitates standardized criteria for monocyte classification.

Purpose of the Study:

• To establish standardized morphological definitions for monocytes and their precursors.
• To harmonize nomenclature for monocyte lineage cells.
• To evaluate the clinical utility of monocytes as biomarkers.

Main Methods:

• Convening the International Council for Standardization in Haematology (ICSH) Monocyte Working Group (MWG).
• Collecting data from global laboratories and conducting an extensive literature review.
• Consensus feedback from the ICSH General Assembly and proposing a three-category morphological classification.

Main Results:

• A proposed three-category morphological classification: blasts and blast equivalents (monoblasts and promonocytes), immature monocytes, and mature monocytes.
• Reaffirmation of morphological analysis, cytochemical staining, and flow cytometry for diagnosis.
• Recognition of emerging automated parameters (e.g., monocyte distribution width - MDW) and ratios (e.g., lymphocyte/monocyte - LMR, neutrophil/monocyte - NMR) as adjunctive biomarkers.

Conclusions:

• Harmonized recommendations aim to enhance diagnostic accuracy for hematologic disorders.
• Standardized criteria will support the development and implementation of machine learning tools in diagnostics.
• These guidelines will facilitate consistent and reproducible reporting of monocyte analysis across laboratories worldwide.