Incidence Patterns of Sequential or Composite Lymphoma: A Population-Based Cancer Registry Study.

The development of multiple histologic types of lymphoma in a single patient has been sporadically reported as sequential or composite lymphoma. However, the incidence pattern of such patients has been rarely evaluated in a large population-based setting. We investigated the incidence of sequential or composite lymphoma based on 11,174 lymphoma records from a population-based cancer registry between 1985-2012 in Nagasaki Prefecture, Japan. We identified 99 lymphoma records were of 49 independent patients other than relapse. The prevalence of the sequential or composite lymphomas in a single patient was 0.44% (95% confidence interval [95% CI], 0.32-0.56%) without sex difference. Among the 49 patients, five (10.2%) were composite/discordant lymphoma. The most frequent "composite lymphoma" was a combination of diffuse large B-cell lymphomas (DLBCL) and adult T-cell leukemia (n = 3). A case of "discordant lymphoma" was a combination of follicular lymphoma on spleen and Waldenström macroglobulinemia on bone marrow. The rest of the patients (n = 44, 89.8% of all composite lymphoma) were "sequential lymphoma" with various combination of lymphoma subtypes on different dates. The major combination of the sequential lymphoma was DLBCL after marginal zone lymphomas (n = 4). In the era of improved survival of lymphoma patients, hematologists should be aware of the development of additional lymphomas.