J. Clin. Exp Hematopathol Vol. 42, No. 2, Oct 2002

Malignant Lymphomas in : 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 . 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, 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), 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 shows that the actual number of patients especially high-resolution image analysis devices gradually increased annually. The data did not and endoscopic equipments, 3) diagnostic indicate an epidemiologically rigorous incidence methods have markedly improved, especially of malignant lymphoma because data were not highly sensitive immunohistochemical techniques sampled evenly,nor were they adjusted by age or using conventional paraffin sections and the population. Nevertheless, the data suggested application of molecular biological methods,and that the incidence of malignant lymphoma 4)the population profile is aging. showed a trend to increase in this local area over It was sometimes difficult to determine the applicable 10 years, since the population of whether the primary site of a lymphoma was this area actually decreased slightly. Several nodal or extranodal,since nodal lymphoma com- other investigations have also indicated that the monly spread to the extranodal region and,con- incidence of malignant lymphoma has been versely, extranodal lymphomas infiltrated into increasing significantly in recent years in the lymph nodes. Therefore,we used the follow-

Japanand in Western countries. It seems ing operational definitions: a lymphoma was certain that the increasing incidence of malignant considered to be extranodal when the main bulk lymphoma is a worldwide trend. Although the and/or primary lesion was found to be present at definitive causes of this trend are uncertain, the an extranodal site in the preliminary examina- following reasons could be considered: 1) novel tion using various clinicopathological proce- concepts, such as extranodal marginal zone B- dures. Table 2 indicates the nodal and

J. Clin. Exp Hematopathol Vol. 42, No. 2, Oct 2002 Malignant Lymphoma in Yamagata

extranodal ratio of malignant lymphoma in that the G-I tract and Waldeyer’s ring (nasophar-

Yamagata Prefecture and other areas,including yngeal region)are the major anatomical sites of

Saitama,Hiroshima,,Korea and Western extranodal lymphoma,not only in Japan but also countries. In the current study,313 cases (38.7%) in Western countries. had a nodal manifestation,and 496 cases (61.3%) were extranodal. The incidence rate of extranodal disease in all malignant lymphomas was quite similar to a recent report from Saitama

Prefecture, but slightly higher than previous

Japanese figures,which had indicated an almost Table 4 indicates the incidence of each

45% frequency. The frequencies of extranodal subtype of the newly published WHO classifica- lymphoma in European and American countries tion for lymphoid neoplasms by re-evaluation of have ranged between 17.6 and 45.6%, so a high 212 recent cases and comparison with other extranodal manifestation seems to be character- reports in Japan. In our area, B-cell lymphoma istic of lymphoma in the Japanese and Korean was dominant (69.8%) as well as other reports, populations, especially those in northeastern but the incidence rate was relatively higher.

Japan (a HTLV-1-nonendemic area). Among the subtypes of B-cell lymphoma, Fig.2 illustrates the annual change in patient diffuse large B-cell lymphoma (DLBCL) con- numbers with nodal or extranodal lymphomas. stituted almost half of the B-cell lymphomas. The number of patients with extranodal This category indicated the highest frequency in lymphomas gradually increased annually,where- all other reports because it is not a uniform as those with nodal lymphomas did not change disease entity and must be composed of a hetero- significantly. Thus, the above-mentioned geneous population. Actually,the WHO classifi- increasing trend of incidence of malignant cationdescribed DLBCL to include several lymphoma seems to be based upon the increasing variants (centroblastic, immunoblastic, T-cell/ incidence of extranodal diseases. histiocyte-rich and anaplastic) and several

The most common extranodal site was the subtypes (mediastinal (thymic) large B-cell gastro-intestinal (G-I) tract (37.9% of all lymphoma,intravascular large B-cell lymphoma extranodal lymphoma) followed by Waldeyer’s and primary effusion lymphoma). In addition,de ring (19.8%), skin and soft tissue (10.1%), nasal novo CD5-positive DLBCL has been recently and oral cavity(5.0%)etc,as shown in Table 3. It received much attention as a clinically and path- is somewhat difficult to directly compare the ogenetically distinct subgroup of DLBCL. data, regarding the preferential sites of Indeed, five CD5＋ cases were included in our extranodal lymphomas, from the different cases classified into DLBCL (6.1% of all DLBCL). reports because there are some discrepancies in Although there are some problems to distinguish the working classifications of anatomical sites between de novo CD5-positive DLBCL and the among the reports. Nevertheless, it is obvious pleomorphic-blastoid variant of mantle cell K. Maeda at al.

lymphoma (MCL)or transformed MCL,they may licular lymphoma. The low frequency of plas- contain some cases of de novo CD5-positive macytoma/myeloma seems to suggest that the

DLBCL. Further attempts to subdivide the pathological diagnostic system may contribute

DLBCL cases would be expected to obtain more poorly to the diagnosis of such diseases in our specific and informative results. local area. Follicular lymphoma was the second most We had a lower percentage of T-cell common subtype, and marginal zone B-cell lymphomas than that in other reports,especially lymphoma of the MALT type,the third common those in Kyushu, as indicated in Table 4. This subtype of B-cell lymphoma. Such a distribution obviously depended upon the much lower inci- pattern was quite similar to the investigation in dence of adult T-cell leukemia/lymphoma

Saitama Prefecture. The frequency of follicular (ATLL). In addition, peripheral T-cell lymphoma in these reports was considerably lymphoma and extranodal NK/T-cell lymphoma, higher than nationwide investigation,as indicat- nasal type, also indicated a lower incidence. In ed in Table 4. The cause of this discrepancy is contrast, angioimmunoblastic T-cell lymphoma unidentified. A westernized living environment revealed a higher incidence rate in Yamagata. may have caused the recent increment of fol- This may represent one of the particular features

J. Clin. Exp Hematopathol Vol. 42, No. 2, Oct 2002 Malignant Lymphoma in Yamagata of T-cell lymphoma in the HTLV-1-nonendemic Western countries: Proceedings of the United area even if it may be partly related to institu- States-Japan Seminar, September 6 and 7,1982, tional bias. in Seattle, Washington. Hum Pathol 14: 745- 772, 1983 The incidence of Hodgkin lymphoma in 3 Wakasa H, Abe M, Nozawa Y : Nodal B-cell Yamagata was only slightly more frequent than lymphomas in Japan-particularly in Tohoku in previous reports as indicated in Table 4. district. Jpn J Clin Oncol 13: 577-590, 1983 Although nodular sclerosis classical Hodgkin 4 Mohri N, Shimamine T : Extra-nodal non- lymphoma occupied over 80% of the total cases Hodgkin’s lymphoma.Nippon Rinsho (Jpn J Clin of Hodgkin lymphoma in Yamagata,the number Med)41: 2569-2571, 1983 (in Japanese) of patients was too small to estimate the real 5 The T-and B-cell malignancy study group: Sta- incidence of subtypes of Hodgkin lymphoma in tistical analysis of clinico-pathological, vir- this area. ological and epidemiological data on lymphoid

Because of limited information and mate- malignancies with special reference to adult rials, we have not yet obtained sufficient and T-cell leukemia/lymphoma: a report of the sec- conclusive results on the incidence and distribu- ond nation-wide study of Japan.Jpn J Clin Oncol tion by a subtype of malignant lymphoma in 15: 517-535, 1985

Yamagata Prefecture. Nevertheless,the present 6 Aozasa K, Tsujimoto M, Sakurai M,Honda M, results suggest some particular features of malig- Yamashita K, Haneda M, Sugimoto A : Non- nant lymphoma in a HTLV-1-nonendemic area of Hodgkin’s lymphomas in Osaka, Japan. Eur J

Japan and should contribute to the verification of Cancer Clin Oncol 21: 487-492, 1985. 7 Nanba K : Geographic pathology of malignant the usefulness of the WHO classification. Fur- ther accumulation of cases, the introduction of lymphoma.In: Iijima S,Ishikawa H,Kageyama epidemiological utilities,such as age adjustment K,Shimamine T,Mori W (eds): “Current Ency- and statistical processing, more objective clopedia of Pathology 18b”.Tokyo,Nakayama- Shoten, 1987, pp. 153-170 (in Japanese) improvement of the diagnostic system and the 8 Ohshima K, Suzumiya J, Sato K, Kanda M, establishment of a case registration system will Haraoka S,Kikuchi M : B-cell lymphoma of 708 be required to obtain a complete conclusion. cases in Japan: incidence rates and clinical

prognosis according to the REAL classification. Cancer Lett 135: 73-81, 1999 Acknowledgements 9 Izumo T,Maseki N,Mori S,Tsuchiya E : Prac- The authors appreciate the staff of the path- tical utility of the revised European-American ological/cytological laboratory section of the classification of lymphoid neoplasms for eleven major hospitals in Yamagata Prefecture, Japanese non-Hodgkin’s lymphomas.Jpn J Can- including Yamagata University Hospital, cer Res 91: 351-360, 2000

Yamagata Prefectural Central Hospital, 10 Nanba K : Epidemiology and geo-pathology of

malignant lymphoma with special emphasis on Yamagata Prefectural Nihon-Kai Hospital, Japanese lymphomas.Nippon Rinsho (Jpn J Clin Yamagata Prefectural Shinjo Hospital, Yamagata Prefectural Kahoku Hospital, Med)58: 535-541, 2000 (in Japanese) 11 Tajima K,Hirose K : Epidemiology of lymphoid Yamagata Municipal Hospital Saisei-kan, Yon- ezawa Municipal Hospital, Nagai Municipal and hematopoietic malignancies in Japan. Gan

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