ABC of clinical haematology: Malignant lymphomas and chronic lymphocytic leukaemia

Introduction

The malignant lymphomas (non-Hodgkin's lymphoma and Hodgkin's disease) are a clinically and pathologically diverse group of cancers of largely unknown cause that are rapidly increasing in incidence. They are highly treatable and sometimes curable. Chronic lymphocytic leukaemia, the commonest adult leukaemia, shares many features with these cancers. The whole group constitutes about 5% of malignant diseases.

Pathology and staging

The non-Hodgkin's lymphomas arise from malignant transformation of lymphocytes, deriving from B cells in about 85% of cases and T cells in most of the rest. Chronic lymphocytic leukaemia is largely a B cell malignancy, but the cell of origin of the Reed Sternberg cell, which characterises Hodgkin's disease, remains uncertain.

Histopathologically, lymphomas comprise an admixture of identical (monoclonal) malignant cells with variable amounts of reactive lymphoid cells and stroma. The lymphomas are variably subcategorised by pathologists into about 20 different types on the basis of conventional cytological staining and special stains to determine subtype and lineage.

A diagnosis of lymphoma (or even B or T cell lymphoma) gives no clue to the natural course of the disease in an individual patient. Clinicians treating these patients take account of the histopathology and the history provided by the patient, as well as many other factors (for example, stage and age), before recommending treatment or advising about prognosis. The complexity of non-Hodgkin's lymphomas requires a simplified management approach, on the …