This is a national multi-centre, experimental, cross-sectional, non-profit study.

Extracellular vesicles are small particles circulating in plasma and documented as key players of intercellular crosstalk thanks to their cargo of proteins, lipids, and nucleic acids. The driving hypothesis of this study is that in Hairy Cell Leukemia-derived extracellular vesicles contribute to the maintenance of the tumor clone through regulation of selected key cells of the tumor microenvironment including immune cells and stromal cells, likely favoring immune evasion and marrow fibrosis. As a consequence, these circulating particles may be instrumental at identifying a biology-related, disease-specific and extracellular vesicle-based signature associated to outcomes.

Inclusion criteria for patients:

• WHO2022-defined diagnosis of Hairy Cell Leukemia.
• Age ≥18 years.
• Signed informed consent.

Inclusion criteria for Healthy Donors:

• Age ≥18 years.
• Volunteers in general good health, free from any disease or serious illness.
• Signed informed consent.

Exclusion criteria

- None

The study population will be composed by Hairy Cell Leukemia patients subdivided as newly diagnosed (n=10), relapsed meeting treatment indications (N=5) and in complete response >2 years (N=10) and by Healthy Donors (n=25), enrolled among volunteers through the non-profit organization AIL Bologna ODV.