J. Clin. Exp Hematopathol Vol. 42, No. 2, Oct 2002 Malignant Lymphomas in Yamagata Prefecture : Retrospective Investigation on Incidence and Preferential Sites, and a Re-evaluation According to Newly-Published WHO (World Health Organization) Classification Kunihiko Maeda，Mikio Matsuda，Fumiaki Yudaand Hito-aki Saitoh The incidence and preferential sites of malignant lymphomas were retrospectively investigated by reviewing archived pathological files (1985 to 1996) in 11 major hospitals in Yamagata Prefecture, a HTLV-1-nonendemic area of Japan. In addition, re-evaluation of 212 recent cases based upon the newly-published WHO classification was performed. The following results were obtained: 1)the actual number of lymphoma patients was increasing annually,2)the incidence rate of extranodal lymphomas was 61.3%,with the gastro-intestinal tract and Waldeyer’s ring being the major preferential sites,3)the incidence of extranodal lymphomas seemed to be increasing annually,whereas that of nodal lymphomas was not, 4) B-cell lymphomas were dominant (69.8%), in a percentage similar to that of a previous nationwide investigation, 5) major categories among the B-cell lymphomas were diffuse large B-cell lymphoma,follicular lymphoma and extranodal B-cell lymphoma of MALT,6)the percentage of T-cell lymphomas was less than that of the nationwide investigation,7)angio-immunoblastic T-cell lymphoma was a major subtype of T-cell lymphoma,and 8)the incidence rate of Hodgkin lymphoma was 5.7% of total malign ant lymphomas. Key words epidemiology, non-HTLV-1 endemic area, B-cell, T-cell, Hodgkin lymphoma iors. It may,therefore,be somewhat difficult to INTRODUCTION establish a complete tumor registration system Malignant lymphoma is a common malig- for malignant lymphomas,and there seems to be nant tumor encountered daily by diagnostic a limitation regarding general epidemiological pathologists. It can originate from almost all studies,which would usually be based upon regis- anatomical sites of the human body, including try data. A geopathological study or an not only lymphoreticular tissues, but also many epidemiological study based upon pathological other sites such as the skin, digestive organs, information may have some advantages in this bone and soft tissues, and even the central ner- regard, as described by Nanba. Although sev- vous system. In addition, it has an extremely eral recent papers have described geo- broad spectrum of biological and clinical behav- pathological or patho-epidemiological traits of malignant lymphomas in Japan, there are only limited reports involving incidence, prefer- Received:Feb 20,2002 Revised: Apr 8,2002 ential sites and recent trends of this type of Accepted:Apr 18,2002 neoplasm in a human T-lymphotropic virus-1 Department of Pathology, Yamagata University School of Medi- (HTLV-I)-nonendemic area of Japan. cine, Yamagata, Japan, Department of Nursing, School of Health The present study was initially designed to Science, Yamagata Prefectural University of Health Science, Yamagata, Japan, Department of Clinical Laboratory, Yamagata look at changes in the incidence of total malig- Municipal Hospital Saisei-Kan,Yamagata,Japan nant lymphoma or disease subgroups, by apply- Address correspondence and reprint request to Kunihiko Maeda, ing accumulated pathological information from Department of Pathology,Yamagata University School of Medicine, 2-2-2 Iida-Nishi,Yamagata 900-9585,Japan Yamagata Prefecture, which is located in a ※注意‼ 地中央のノンブル ごとの通しノンブル K. Maeda at al. HTLV-1-nonendemic area of Japan. We anal- yzed retrospectively the primary anatomical sites, along with the actual patient numbers, by reviewing files of pathological reports archived in the pathological laboratory section of the 11 212 recent cases (1996 to 2001), which were major hospitals in the Prefecture. In addition,the diagnosed as malignant lymphomas or related distribution of each subtype of the newly publi- diseases at the Department of Pathology, shed World Health Organization (WHO)classifi- Yamagata University School of Medicine,includ- cation of lymphoid tumorswas estimated by a ing consulting cases sent from other hospitals, re-evaluation of the recent cases. were re-examined for the application of the new- Our results suggested some particular trends ly established WHO classification of tumors of for malignant lymphomas in the subjected local the haematopoietic and lymphoid tissues. For area, and might contribute to the establishment this examination,re-consideration of the clinical of a therapeutic strategy against malignant and laboratory information, conventional mor- lymphomas in a HTLV-1-nonendemic area of phological observation by hematoxylin and eosin Japan. sections, and immunohistochemical phenotyping were undertaken. Phenotyping was achieved in principle using formalin-fixed, routinely- MATERIALS AND METHODS processed paraffin sections and the labeled streptavidin-biotin (LSAB) labeling system de- scribed below. The antibodies used are listed in A total of 807 cases of malignant lymphoma Table 1. In addition, flow-cytometry examina- and related disorders were obtained from a com- tion,chromosomal analysis,southern blot analy- prehensive review of the archived files of the sis of immunoglobulin and T-cell receptor genes, pathological diagnostic reports from 1985 to 1996, and polymerase chain reaction (PCR)analysis of which were in the custody of the pathological/ the variable regions of the immunoglobulin cytological laboratory sections of the eleven heavy chain genes were conducted where pos- major hospitals in Yamagata Prefecture: sible. Yamagata University Hospital (Yamagata), Yamagata Prefectural Central Hospital (Yamagata), Yamagata Prefectural Nihon-Kai Hospital (Sakata),Yamagata Prefectural Shinjo The immuno-phenotypes of the tumor cells Hospital(Shinjo),Yamagata Prefectural Kahoku were examined immunohistochemically by the Hospital (Nishi-Murayama County), Yamagata LSAB immunohistochemical system,as previous- Municipal Hospital Saisei-kan (Yamagata),Yon- ly reported. Briefly, the routinely-processed ezawa Municipal Hospital (Yonezawa), Nagai paraffin sections were dewaxed in xylene, rehy- Municipal Hospital(Nagai),Tsuruoka Municipal drated through a graded series of ethanol and Sho-nai Hospital (Tsuruoka), and Tsuruoka submerged in methanol containing 0.3% HOto Kyoritsu Hospital(Tsuruoka). The patient’s age, quench endogenous peroxidase activity. Then,if sex,the anatomical site of the excised specimen, needed,they were processed by suitable antigenic and brief clinical information such as manifesta- retrieval procedures,such as microwave irradia- tions,physical/laboratory findings and data from tion in 0.01 M citrate buffer or proteolytic diges- image examinations,along with the pathological tion with trypsin. After being thoroughly rinsed diagnosis of each case were registered. Plural with phosphate-buffered saline (PBS), they were numbers of specimens from the same patient incubated with a protein blocking agent were counted as one case if they were taken (UltraTech HRP Streptavidin-Biotin Universal within a year. To improve the reproducibility of Detection System,Immunotech,Marseilles,Fran- data, myeloid leukaemia, histiocytic/dendritic ce) to prevent non-specific binding of the anti- cell tumor and related diseases were excluded bodies. They were then incubated overnight with because of the difficulty for our reviewing system each primary antibody at 4°C. The following to accurately define the incidence of these cases. day, they were washed three times in PBS and incubated with biotinylated secondary antibody J. Clin. Exp Hematopathol Vol. 42, No. 2, Oct 2002 Malignant Lymphoma in Yamagata ε β β α ε (UltraTech HRP Streptavidin-Biotin Universal same isotype were used instead of the primary Detection System) for one hour at ambient tem- antibody. In addition,control experiments were perature. Sections were then washed three times performed to determine the reactivity of the in PBS and incubated with peroxidase (PO)- biotinylated secondary antibody and PO-labeled labeled streptavidin (UltraTech HRP streptavidin, and to quantify endogenous perox- Streptavidin-Biotin Universal Detection System) idase activity. for one hour at ambient temperature. After the incubation, sections were washed in PBS and in RESULTS AND DISCUSSION Tris-HCl buffer (0.05 M, pH 7.6) and the PO activity was developed using 0.05% diaminoben- zidine with 0.03% HOas described by Graham & Karnovsky. Sections were next counter- stained with hematoxylin and mounted with Permount (Fisher Scientific, Fair Lawn, NJ) for A total of 807 cases of malignant lymphomas light microscopic observation. or related disorders were registered from a retro- As a control,inappropriate antibodies of the spectively review of the archived files of patho- K. Maeda at al. Fig. 1. Change in annual number of patients with Fig. 2. Change in annual number of patients with malignant lymphoma in Yamagata Prefec- nodal or extranodal lymphoma in ture from 1985 to 1996. Yamagata Prefecture from 1985 to 1996. logical diagnostic reports from 1985 to 1996 in the cell lymphoma of mucosa-associated lymphoid eleven major hospitals in Yamagata Prefecture. tissue (MALT), extranodal natural killer (NK)/ The annual change in the number of patients T-cell lymphoma,nasal type and anaplastic large who were diagnosed with malignant lymphoma cell lymphoma have been established, 2) better or related disorders is shown in Fig. 1. This examination techniques have been developed, graph