[Malignant lymphoma]

The WHO classification, considered as a bible for lymphoma diagnosis, is a list of disease units. It is expected that it will fully classify all diseases based on indicators with objectivity of constants, even in the present state, in which it cannot be said that the source, causes, and tumorigenesis mechanisms have been identified for all neoplasms. The indicators are the histology, phenotype, genotype, and clinical picture. In the current WHO classification, these indicators are described for each diseases unit, and considered as diagnostic items. While the importance of items which serve as indicators differ depending on each illness, the pathologic centering on a morphological finding does not change for lymphoma diagnosis in accordance with this WHO classification. An indispensable factor in order to evaluate this objective of pathologic diagnosis is phenotypic and genotype assessment. A phenotype is analyzed by immunohistochemistry techniques, and a genotype is clarified by various gene chromosome tests. Diagnostic applications using these test results are developed as follows: 1. Histological diagnosis based on the immunohistochemical features of lymphoma cells, 2. Identification of oncogene products, 3. Evaluation of biological prognostic factors, 4. Analysis of the inflammatory microenvironment of tumor cells. This paper describes all items.