Book 4 - Self Instructional Manual for Cancer Registrars - SEER ...

Malignant and Benign TumorsBenign tumors of lymphoid tissue are rare. Those of the lymphatic vessels, as you have alreadylearned, are known as lymphangiomas. Cancer registries may, or may not, elect to include thesetumors.MalignantLymphomasLymphomas are malignancies of the lymph nodes and other lymphatic structures, such as thespleen, thymus, Waldeyer's ring (tonsils), Peyer's patches (ileum) of the small intestine, and lymphoidnodules of the appendix as well as extralymphatic/extranodal sites such as stomach and skin.There are two principal kinds of lymphomas:1) Hodgkin's disease, which commonly arises in lymph nodes and other lymphatic structures,makes up 19% of all lymphomas. Of the Hodgkin's disease cases reported, 99% are nodal.2) Non-Hodgkin's lymphoma (NHL), which frequently arises in extralymphatic/extranodal sitesas well as in lymph nodes and other lymphatic structures, makes up 81% of all lymphomas. Of thenon-Hodgkin's lymphoma cases reported, 77% are nodal and 23% are extranodal.The classification of NHL is discussed in detail in ICD-O-2 including a discussion of extranodal andnodal lymphomas.89