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Non-Hodgkin’s lymphomas (NHL) are cancers of mature B, T, and NK cells. They were distinguished from Hodgkin lymphoma (HL) upon recognition of the Reed-Sternberg (RS) cell, and differ from HL with respect to their biologic and clinical characteristics. Whereas ~80–85% of patients with HL will be cured of their lymphoma by chemotherapy with or without radiotherapy, the prognosis and natural history of NHL tends to be more variable. NHL can be classified as either a mature B-NHL, or a mature T/NK-NHL depending on whether the cancerous lymphocyte is a B, T, or NK-cell, respectively. Within each category are lymphomas that grow quickly and behave aggressively, as well as lymphomas that are more indolent, or slow growing in nature. For a list of the World Health Organization (WHO) classification of lymphoid neoplasms, see Table 104-1.
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EPIDEMIOLOGY AND ETIOLOGY
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In 2017 over 72,000 new cases of NHL were diagnosed in the United States, about 4% of all new cancers in both males and females making it the eighth and ninth most common cause of cancer-related death in women and men, respectively. The incidence is nearly 10 times the incidence of Hodgkin’s lymphoma. There is a slight male-to-female predominance and a higher incidence for Caucasians than for African Americans. The incidence rises steadily with age, especially after age 40, but lymphomas are also among the most common malignancies in adolescent and young adult patients. The incidence of NHL has nearly doubled over the last 20–40 years, and continues to rise by 1.5–2% each year. Patients with both primary and secondary immunodeficiency states are predisposed to developing non-NHL. These include patients with HIV infection; patients who have undergone organ transplantation; and patients with inherited ...