A haemopathy is a blood disease liable to affect the red blood cells, the white blood cells and/or the platelets. There are benign haemopathies, such as anaemia and certain haemoglobinopathies, and malignant haemopathies. These include leukaemia or “blood cancers”, lymphomas which are cancers of the lymph glands or the spleen, and myelodysplasic and myeloproliferative syndromes in which the former means there is a malfunctioning of blood cell production while the latter means excessive blood cell production. In 2012, there were 35,000 new cases of malignant haeomopathies in France. More than 2/3 of cases were lymphoid haemopathies.

Histology is a specific area of study dedicated to the microscopic structure of tissues and organs. It is called anatomopathology and is performed by an anatomical pathologist when the study focuses on the tissue of a diseased or deceased person. The basic technique of histology is as follows: the tissue is removed (by biopsy, puncture, dissection, etc.) and then conserved (fixation or freezing), after which it is sliced into thin strips, coloured and observed through a microscope.

Histology is used for both biological and medical research. In oncology, it determines whether a tumour is malignant or not. If the tumour is malignant, it specifies its type (carcinoma, sarcoma, etc.) and it degree of seriousness: aggressiveness, grade, stage. Thus it contributes to evaluating the prognosis of the cancer and defining the treatment suitable for the patient.
Histology is one of the tools of research used to study the mechanisms by which tumours develop.

Histones are proteins closely linked to DNA and are the main protein constituents of chromosomes.

Histones play an important role in packaging and folding DNA. They compress DNA around structures called nucleosomes: the DNA is wound round histones like a thread around a bobbin.

Histones undergo different kinds of modifications that determine the structure of the chromatin.