Not another lymphoma classification!

Distribution and incidence rates of lymphoid neoplasms according to the REAL classification in a single institution. A prospective study of 940 cases

Recently, a new classification system for lymphoid neoplasms, known as the REAL classification, has been proposed. Our aim is to know the distribution of lymphoid neoplasms according to this schema and compare it with the Updated Kiel classification. We also estimate incidence rates of lymphoid neoplasms in our area. From January 1993 to November 1996, 940 patients were diagnosed of lymphoid neoplasm in our center. Histologic material was prospectively classified according to both the REAL and the Updated Kiel classifications. According to the REAL classification, distribution of all cases of lymphoid neoplasms was as follows: 73.6% B-cell neoplasm, 9.4% T-cell neoplasms, 9.6% Hodgkin's disease and 7.4% unclassifiable. Considering only non-Hodgkin's lymphomas (NHL), 87.2% of cases could be categorized according to the REAL and 77.7% with the Updated Kiel classification. These figures differed due to unrecognized categories in the Kiel schema. Annual incidence rate per 100,000 inhabitants was 20.1 for lymphoid neoplasms, and NHL alone was 9.0. In conclusion, the REAL classification allowed us to categorize more cases of NHL than did the Updated Kiel classification, fundamentally because of the inclusion of some recently described entities.

Hematopoietic and lymphatic malignancies in vehicle mechanics

Although it is generally acknowledged that benzene causes leukemia, especially acute myeloid leukemia, considerable divergences persist in the assessment of the leukemia risk due to occupational low-level benzene exposure. Specifically, the risk for vehicle mechanics is considered by some authors as being nondetectable with epidemiologic methods, whereas others calculated that the incidence rate of leukemia (all types) in vehicle mechanics is increased more than 60 times. The purpose of this review is to examine the publications on this topic in light of criteria for causal inference and to discuss the possible role of bias, confounding factors, and chance. The results of this analysis reveal that there are surprisingly few epidemiologic observations supporting an increased incidence of leukemia in vehicle mechanics. Apparently, publications suggesting a leukemogenic effect of low-level benzene exposure in garage mechanics are more often quoted than their negative counterparts, although they are not better designed.

A Clinical Evaluation of the International Lymphoma Study Group Classification of Non-Hodgkin's Lymphoma

The recognition of several new types of non-Hodgkin's lymphoma (NHL) in recent years has led to proposals for changing lymphoma classifications, including a new proposal put forth by the International Lymphoma Study Group (ILSG). However, the clinical significance of the new entities and the practical utility of this new proposal have not been studied. Therefore, we performed a clinical evaluation of the ILSG classification. A cohort of 1,403 cases of NHL was organized at nine study sites around the world and consisted of consecutive patients seen between 1988 and 1990 who were previously untreated. A detailed protocol for histologic and clinical analysis was followed at each site, and immunologic characterization as to T- or B-cell phenotype was required. Five expert hematopathologists visited the sites and each classified each case using the ILSG classification. A consensus diagnosis was also reached in each case, and each expert rereviewed a 20% random sample of the cases. Clinical correlations and survival analyses were then performed. A diagnosis of NHL was confirmed in 1,378 (98.2%) of the cases. The most common lymphoma types were diffuse large B-cell lymphoma (31%) and follicular lymphoma (22%), whereas the new entities comprised 21% of the cases. Diagnostic accuracy was at least 85% for most of the major lymphoma types, and reproducibility of the diagnosis was 85%. Immunophenotyping improved the diagnostic accuracy by 10% to 45% for a number of the major types. The clinical features of the new entities were distinctive. Both the histologic types and the patient characteristics as defined by the International Prognostic Index predicted for patient survival. In conclusion we found that the ILSG classification can be readily applied and identifies clinically distinctive types of NHL. However, for clinical application, prognostic factors as defined by the International Prognostic Index must be combined with the histologic diagnosis for appropriate clinical decisions.

Cytogenetic findings in 175 patients indicate that items of the Kiel classification should not be disregarded in the REAL classification of lymphoid neoplasms

Cytogenetics have proved to be a valuable tool for classifying systemic lymphatic neoplasms, as this technique allows different stem line aberrations and clonal developments to be distinguished. This study was designed to analyze how far groups defined according to common cytogenetic features correlated with their position in either the Kiel (KC) or the REAL classification. Cytogenetic analyses were performed on material from 175 patients with lymphoid neoplasms (LN). Samples were prepared from peripheral blood and bone marrow in acute lymphoblastic leukemia (ALL), from bone marrow in multiple myeloma (MM), and from lymph node biopsies in lymphomas. The results of this study support the inclusion of ALL, MM, and extranodal lymphomas into a comprehensive classification, because their chromosomal aberrations were always characteristic for LN. From the cytogenetic point of view, a subgroup of ALL appears as a leukemic manifestation of lymphoblastic lymphoma. MM have structural aberrations of chromosomes 1, 11, and 14 and secondary aberrations of chromosomes 3, 6, 7, 12, 13, and 18, all of which are characteristic for lymphatic disease. The groups with follicle center cell lymphoma and mantle cell lymphoma correlate well with our results both in the low-grade subtype and in the blastic variant type, the majority of cases demonstrating t(14; 18) and its variants and t(11; 14), respectively. In contrast, the group of diffuse large B-cell (DLB) lymphomas proved to be heterogeneous on the basis of our cytogenetic results. Accordingly, we would suggest keeping the immunoblastic lymphoma (IB) subtype defined by the KC. IB demonstrates no stem line aberration in common with any other group and seems to be characterized by stem line aberrations involving chromosomes 3 and 6. As some DLB lymphomas have a t(14;18) or variant translocations involving chromosome 18, they should either be separated as a subgroup or included into the group of follicle center lymphomas.