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Chronological changes in incidences of polymorphic reticulosis in Korea and Japan
M Ohsawa1, N Shingu, H Inohara
1Department of Pathology, Osaka University Medical School, Suita, Osaka, Japan.
Abstract:
Lethal midline granuloma (LMG) is a clinical term, which describes a group of diseases histologically comprising Wegener's granulomatosis, polymorphic reticulosis (PR), and malignant lymphoma of the ordinary type (ML). PR is a variant of ML, and is considered to be a type of NK/T cell lymphoma. Our previous study revealed the clustering of patients with PR in East Asia including China, Korea and Japan. However, the frequency rate of PR varied even among these countries, with that of Korea being approximately 5 times higher than that of Japan. In the present study, we examined the incidences of each type of LMG, especially PR, in Korea (Yonsei University) and Japan (59 university hospitals) over time. A total of 102 cases and 655 cases of LMG admitted to Yonsei University, Korea from 1977 to 1996 and 59 university hospitals in Japan between 1965 and 1996, respectively, were examined. The frequency rate of PR per 100,000 outpatients of ears, nose and throat (ENT) clinics in Korea decreased from 40 to 20 between the periods of 1977-1989 and 1990-1996. However, there were no significant changes in Japan during the period studied.
Insights
The incidence of polymorphic reticulosis (PR), a type of NK/T cell lymphoma, has decreased in Korea but remained stable in Japan. This study compares PR rates in East Asian countries.
Area of Science:
- Pathology
- Oncology
- Epidemiology
Background:
- Lethal midline granuloma (LMG) encompasses Wegener's granulomatosis, polymorphic reticulosis (PR), and malignant lymphoma (ML).
- Polymorphic reticulosis (PR) is classified as an NK/T cell lymphoma and previously showed a higher prevalence in East Asia.
- Significant variations in PR frequency were noted among East Asian countries, with Korea exhibiting a notably higher rate than Japan.
Purpose of the Study:
- To investigate the temporal trends in the incidence of LMG subtypes, with a specific focus on PR.
- To compare the epidemiological patterns of PR in Korea and Japan over several decades.
Main Methods:
- Retrospective analysis of 102 LMG cases at Yonsei University, Korea (1977-1996).
- Analysis of 655 LMG cases from 59 Japanese university hospitals (1965-1996).
- Calculation of PR incidence per 100,000 ENT outpatients.
Main Results:
- The incidence rate of PR in Korea declined from 40 to 20 per 100,000 ENT outpatients between 1977-1989 and 1990-1996.
- No significant temporal changes in PR incidence were observed in Japan during the study period (1965-1996).
Conclusions:
- The epidemiological landscape of PR, an NK/T cell lymphoma, shows distinct temporal changes in Korea compared to Japan.
- Further research is warranted to understand the factors contributing to the declining PR incidence in Korea.