Low grade lymphomas in the elderly.

Aging is considered to play an important role in the pathogenesis of non-Hodgkin's lymphoma (NHL). Recent epidemiological studies, both in the United States and worldwide, show an increasing incidence of NHL, with the increase also marked in the elderly population. Two hundred thirty-two patients with NHL, aged 60 years and older (44 percent female and 56 percent male), have been analyzed retrospectively. These patients represented 39 percent of all NHL cases seen over a seven-year period at a single institution. Among the elderly cases, 81 (35 percent) were classified as low-grade NHL, with 44 (19 percent) small lymphocytic lymphoma/chronic lymphocytic leukemia, 2 (1 percent) small lymphocytic lymphoplasmacytoid, 13 (6 percent) diffuse small cleaved including mantle cell, and 22 (9 percent) follicular small cleaved and mixed cell types. Although the indolent lymphomas are currently treated similarly, recent studies indicate differences in pathogenesis and survival among the classic subtypes. Also, several new low-grade clinicopathologic entities have been described. The clinical, morphologic, immunophenotypic, and genetic features of the classic and newer low-grade lymphomas are discussed.