Malignant lymphoma in Hawaii-Japanese: A retrospective morphologic survey

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Abstract
A retrospective morphologic survey (1973–1983) of 146 cases of malignant lymphoma among the Hawaii-Japanese (migrant Japanese and their offspring) was conducted to determine whether differences in the incidence and cytologic types of malignant lymphoma exist when compared to those of native Japanese (lifetime residents of Japan). The age-adjusted incidence rates for malignant lymphoma among the Hawaii-Japanese were similar to rates for U.S. whites. However, higher rates for follicular centre cell (FCC) lymphoma with a follicular pattern were observed in the Hawaii-Japanese population when compared with rates for native Japanese. On the basis of the cytologic types of the Lukes–Collins classification, non-Hodgkin's lymphomas among the Hawaii-Japanese resembled those of Western countries, rather than those of Japan. B-cell lymphomas predominated (72 per cent), while T-cell types comprised 23 per cent of cases. Follicular centre cell types were encountered most often (59 per cent), and the small cleaved FCC subtype was the most common (30 per cent). The high degree of follicularity (29 per cent) was at variance with the consistently low rates reported in Japan. This may be explained, in part, by higher rates of nodal lymphomas among the Hawaii-Japanese. Of the T-cell lymphomas, diffuse large cell types (T-cell immunoblastic sarcoma, T-IBS), often with cytologic pleomorphism, were relatively frequently encountered (16 per cent), and comprised 15 per cent of non-Hodgkin's lymphomas; this observation necessitates special clinical and epidemiologic consideration in view of the large Japanese migration to Hawaii from HTLV-I endemic regions of southern Japan. No registered cases of non-Hodgkin's lymphoma or of Hodgkin's disease were documented in Hawaii-Japanese subjects under the age of 15 years. The age-adjusted incidence rates for Hodgkin's disease among the Hawaii-Japanese were similar with those of native Japanese. Nodular sclerosis was the most frequent histologic subtype. The difficulty in distinguishing between Hodgkin's disease and non-Hodgkin's lymphoma, particularly when immunologic cell surface markers are not available, is addressed. Low rates for chronic lymphocytic leukemia among the Hawaii-Japanese were confirmed. Not one well-documented case was identified in the 11-year period surveyed.