ABSTRACT
Approximately one-third of non-Hodgkin lymphomas (NHL) arise from sites other than lymph nodes, spleen, or the bone marrow and even from sites which normally contain no native lymphoid tissue.1,2 The exact designation of extranodal lymphoma is controversial, particularly in the presence of both nodal and extranodal disease. Different criteria for the diagnosis of primary extranodal lymphoma have been proposed, most of them initially made for the gastrointestinal lymphomas and later extrapolated to
The first definition was proposed by Dawson for gastrointestinal lymphomas,3 and later refined by Lewin4 and Herrmann.5 The original Dawson criteria defined primary gastrointestinal lymphoma, a presentation with main disease manifestation in the gastrointestinal tract, with regional lymph node involvement only, with no peripheral lymph node involvement, and no liver or spleen involvement. Later these criteria were relaxed to allow for contiguous involvement of other organs (e.g., liver, spleen) and for distant nodal disease, providing that the extranodal lesion was the presenting site and constituted the predominant disease bulk. More recently, it has been proposed to operationally designate as extranodal those lymphomas where,
Introduction 1010 Nodal versus extranodal lymphomas 1010 Epidemiology and etiopathogenesis 1011 Histologic subtypes at different sites 1011 Clinical characteristics and outcome 1012 Approach to management of extranodal lymphomas 1014 Patient assessment 1014 Principles of treatment 1016 Surgery 1016 Radiation therapy 1016 Chemotherapy and combined modality therapy 1016
(chemotherapy/radiation therapy) Management of relapse 1016 Specific extranodal presentations 1017 Gastrointestinal tract lymphoma 1017 Epidemiology and classification 1017 Diagnosis and staging procedures 1017 Clinical management 1018 Diffuse large B cell lymphoma of the stomach 1018 Marginal zone B cell lymphomas of the 1019
gastrointestinal tract Primary intestinal lymphomas 1019 Genitourinary tract lymphoma 1020 Testis lymphoma 1020
Lymphoma of the kidney 1021 Lymphoma of the bladder, urethra, and prostate 1021 Primary lymphomas of the female genital tract 1022 Lymphoma presenting in the head and neck region 1022 Waldeyer’s ring lymphoma 1022 Thyroid lymphoma 1023 Salivary gland lymphoma 1023 Lymphoma of the ocular adnexa (orbital lymphoma) 1023 Paranasal sinuses and nasal cavity lymphoma 1024 Plasmablastic lymphoma of the oral cavity 1025 Primary lymphomas of the upper airways 1025 Primary central nervous system lymphoma 1025 Primary ocular lymphoma 1026 Primary leptomeningeal lymphoma 1026 Primary extradural lymphoma 1026 Primary extranodal lymphomas at other sites 1027 Primary cutaneous lymphomas 1027 Breast lymphoma 1028 Primary lymphoma of the bone 1028 Primary lymphoma of the lung 1029 Lymphomas arising from the thymus 1029 Other uncommon primary extranodal sites 1029 Key points 1031 References 1031
nant’ extranodal component, to which primary treatment must often be directed.6 The choice of a strict or a liberal definition of extranodal lymphoma inevitably introduces a selection bias. A study from a population-based lymphoma registry in the Netherlands showed that the frequency of extranodal NHL fluctuated from 20 percent to 34 percent depending on the adopted definition criteria.7
