ERIC 2024 | The tests that are needed to make a definitive diagnosis of CLL

The tests that are needed to make a definite diagnosis of CLL are quite complex and this is why a lot of education and training is needed to ensure that hematologists are familiar with the diagnostics. So number one, the full blood count and the blood film are really the starting point. Any patient with a persistent lymphocytosis of more than three months should have a full blood count and a blood film. And then if there are suspiciously looking cells on the blood film that are classical with a smear cell aspect of the blood film, they should be referred for flow cytometry. Flow cytometry will definitely establish the diagnosis of CLL and the essential criteria have been recently redefined in the WHO book and it’s an essential criteria. So it’s the WHO that says that flow cytometry is essential. We hope that this will encourage governments and ministries of health to put in the infrastructure for making diagnosis of this important blood cancer and also the other leukemias, of course, in particular childhood lymphoblastic leukemia that is a very big problem in emerging countries and clearly needs very precise diagnosis, as well as CLL, CML, and acute myeloid leukemia. So that is really establishing the diagnosis. When it then comes to unclear cases, atypical cases, sometimes fluorescence in situ hybridization or FISH is required to differentiate between CLL and mantle cell lymphoma. But more importantly, almost, the FISH and the sequencing are required to identify mutations in TP53 and also to do immunoglobulin mutation analysis. And those two tests are needed because they help the clinicians to identify patients who really should not have chemotherapy. And in many parts of the world, chemotherapy is the only treatment that is available. And giving patients with TP53 abnormalities chemotherapy is very detrimental and it does not work and it makes people very often unwell from the chemotherapy. They get additional side effects, bone marrow failure, so it’s a very bad thing to do but it still happens of course because of the lack of access to genetic testing.