A cytological examination is often the initial diagnostic test performed in the case of malignant haemopathies, along with a complete blood count.
This analysis can provide or confirm a diagnosis and help determine the follow-up tests to be performed. The cells found in blood or bone marrow are stained with May-Grünwald-Giemsa stain and, if necessary, with other stains (Perls, myeloperoxidase). The qualitative and quantitative analyses of these cells under the microscope are performed by a specialised cytologist.
Cytology also plays a role in the non-malignant context (e.g. drepanocytosis, screening for schizocytes, lysosomal storage disease, etc.)
Immunophenotyping by flow cytometry is used to investigate the antigens expressed by cells found in the blood or bone marrow. The expression profile thus obtained makes it possible to characterise the cells as normal or pathological, mature or immature (blasts), B or T lymphoids, etc.
This examination complements the myelogram in the diagnosis of acute leukaemia and myeloma, and facilitates the differential diagnosis of monocytosis. It is essential for the classification of chronic lymphoproliferative syndromes: LLC (calculation of the Matutes score, prognostic marker CD38), follicular lymphoma, hairy cell leukaemia, mantle cell lymphoma, etc.