The epidemiologic features of Hodgkin's disease vary with age at clinical onset. Three age periods can be distinguished: 0–14, 15–34, and 50 and over. The epidemiologic features of the disease in these 3 periods are summarized in Table 9. Bimodality of the age incidence curve augments the idea that the entity as now described is heterogeneous.
Two hypotheses are proposed on the basis of the epidemiologic evidence and a brief consideration of pathology and prognosis. First, patients now categorized as having Hodgkin's disease include at least 3 subgroups, the etiology of which may be quite distinct. Second, Hodgkin's disease in young adults is a chronic granulomatous inflammation, whereas that occurring in persons over 50 is a neoplasm.