ABSTRACT
Leukemia versus lymphoma 4 Hodgkin’s versus non-Hodgkin’s lymphomas 4 Defining diseases 5 Neoplasia of the immune system 5 Role of lymphocytes 5 Lymphocyte ontogeny and immune responses 6 Lymphoid neoplasms resemble their normal cell 7
counterparts Abrogation of normal apoptotic pathways 7 Clonal nature of lymphoid neoplasia 7 Epidemiology of lymphoid neoplasia – the 8
macroenvironment Geographic and temporal differences 11 Anatomic locations of lymphoid neoplasia – the 12
microenvironment Role of normal cells in maintaining lymphoid neoplasms 12 The spectrum of lymphoid neoplasms and their classification 13 Precursor and mature cell neoplasms 13
Mature B cell neoplasms 13 Mature T cell neoplasms 13 Molecular pathogenesis of lymphoid neoplasms 14 Major types of translocation 14 Occurrence of pathogenetic lesions in normal individuals 15 Genetic lesions in immature lymphoid neoplasms 15 Genetic lesions in mature lymphoid neoplasms 15 Different genetic lesions may lead to similar 16
pathobiologic consequences Genesis of molecular lesions 16 Molecular profiling 17 Clinical features 17 Associated conditions not due to mass lesions 18 Age 18 Diagnosis 19 Management 19 Choice of therapy 20 Prognosis 20 Key points 21 References 21
The first modern description of lymphoid neoplasia is usually accepted to be that of Thomas Hodgkin in 18321
(although some of Hodgkin’s cases were, over 100 years later, shown to be tuberculosis). Hodgkin’s disease, like Virchow’s subsequent term lymphoma, was initially used to designate swollen lymph nodes of unknown cause (a much broader category than today, given the limited diagnostic tools then available). At that time, the concept of lymphoid neoplasia was poorly developed. This is not surprising. The malignant tumors of lymphocytes, their precursors and their progeny differ in many important respects from other diseases referred to as cancer since they arise from a widely dispersed ‘system’ comprising more or less organized congregations of lymphoid tissue and
the tissues of the body. Thus, the concept of local invasion and blood-borne metastases that works well for most ‘solid tumors’ is more difficult to apply in the case of lymphoid neoplasms, a high proportion of which, by virtue of the migratory properties of their normal cell counterparts, are widespread from the outset.
