Peripheral T-cell lymphomas: an evaluation of reproducibility of the updated Kiel classification

Histological Evaluation of Thyroid Carcinomas: Reproducibility of the «Who» Classification

Aims and Backgrounds

Thyroid carcinomas display several pathologic features, show different behavior and necessitate different treatment; thus correct classification is mandatory.

Methods

The kappa statistic was used as a measure of agreement in a panel of seven pathologists who reviewed 200 cases of thyroid tumors.

Results

Overall agreement was 83 % (k = 68). Good agreement was found for anaplastic (k = 0.85) and papillary carcinomas (k = 0.81); agreement for medullary carcinoma was acceptable (k = 0.80), suboptimal for other (k = 0.67), and poor for follicular carcinoma (k = 0.54).

Conclusions

Central pathology review of thyroid carcinomas is recommended when clinical and epidemiologic trials are planned.

Peripheral T-cell lymphoma classification: the matter of cellular derivation

Peripheral T-cell lymphomas (PTCLs) represent approximately 12% of all non-Hodgkin's lymphomas in Western countries. They are quite heterogeneous as far as morphology and phenotype are concerned. Furthermore, until now, PTCLs could not be referred to specific normal counterparts, in contrast to B-cell-derived non-Hodgkin's lymphomas. In particular, in the last edition of the WHO classification of Tumors of the Hematopoietic and Lymphoid Tissues, for the majority of nodal PTCLs (including the not otherwise specified type and anaplastic large-cell lymphoma), the postulated cell of origin remained undefined. However, in the last few years, high-throughput genomic techniques, especially gene-expression profiling, have allowed us to better define the relationship between some entities and the different T-cell subpopulations. Consequently, it has become possible to clearly define, for example, the association between angioimmunoblastic T-cell lymphoma and T-follicular helper cells. In addition, within PTCLs/not otherwise specified, different subgroups were identified based on their similarity to different cellular counterparts, including T-helper, T-cytotoxic and T-follicular helper cells. In this article, based on their own experience as well as up-to-date literature, the authors revise the concept of PTCL classification by specially focusing on their cellular counterparts and discuss the possible clinical relevance of such an approach.

Incidence and outcomes of the peripheral T-cell lymphoma subtypes in the United States

Peripheral T-cell lymphomas (PTCL) represent a small subgroup of non-Hodgkin lymphomas historically difficult to diagnose. We conducted a comprehensive assessment of 3287 PTCL cases diagnosed from 1992 to 2005 in 13 Surveillance, Epidemiology and End Results registries. Incidence trends, age-adjusted incidence rates and relative survival rates were compared across the study period, and by sex, race and age groups. From 1992 to 2005, PTCL incidence increased by 280%. Age-adjusted incidence rates were higher in males (Male/Female incidence rate ratio (IRR) 1.8) and in Blacks (Black/White IRR 1.2). Asian predominance was pronounced for extranodal NK/T-cell lymphoma, nasal type. Whites had higher 5-year survival than other racial groups for most histologic subtypes; however, the differences were not statistically significant. The variance in incidence rates and outcomes across PTCL subtypes support the pursuit of ongoing research to identify the etiology, pathophysiology, treatment patterns and differences in treatment response for PTCL subsets.

Pathologist interobserver variability of histologic features in childhood brain tumors: results from the CCG-945 study

In the Children's Cancer Group-945 trial, study design allowed estimation of overall interpathologist observational agreement for 6 histologic features frequently used in brain tumor diagnoses. We evaluated agreement between pairs of 5 experienced neuropathologists, who had knowledge of the general diagnoses prior to slide readings. We performed this study in an attempt to further improve pathologist interinstitutional agreement. The features mitosis, necrosis, and giant cells had "fair" overall kappa estimates of reproducibility of around 0.5, while endothelial proliferation had only a "poor" overall kappa of 0.35. The Rogot reproducibility index averaged 0.5 for pleomorphism and hyperchromia. The upper bounds for the 10 pair summary agreement estimates were at best 0.65 ("good") for all 6 features. These relatively low-reproducibility estimates for the very small number of histologic features being assessed in tumors institutionally diagnosed as high-grade gliomas indicate that neuropathologists either used different operational definitions or interpreted them differently. We found that we could rank the histologic features from best to worst agreement among study pathologists as necrosis, giant cells, mitosis, endothelial proliferation, hyperchromic nuclei, and pleomorphic cells. We suggest that neuropathologists involved in multi-institutional studies of putative therapies not discard these traditional histologic features, but rather develop standardized operational definitions and measure their variability before beginning the studies. Only after such histologic feature variability studies are conducted will we have the data to identify specific histologic features of value to clinicians and researchers. Agreement and strict adherence to improved nonsubjective diagnostic criteria would improve histologic feature reliability and, consequently, their usefulness in studies.

'Normal counterparts' of nodal peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCL) have been difficult to classify. A homogeneous principle of classification is still lacking, partly because lymph node compartments containing functionally distinct T-cell subsets have not been identified. A correlation to differentiated T-cell subsets, as CD4(+) or CD8(+) cells as well as cytotoxic populations has not revealed clinically meaningful entities. Upon antigen encounter, mature T-cells pass through distinct stages characterized by their surface molecule expression. Naïve T-cells are CD45RA(+)/CD45R0(-)/CD27(+)/CCR7(+), however, after antigen contact CD45RA expression is replaced by CD45R0. They differentiate to central memory cells, which retain CD27 and CCR7, or to effector-memory cells, which loose expression of both molecules depending on the strength of the antigen interaction. Immunohistological analysis of PTCL showed an effector or effector-memory cell phenotype (CD45RA(-)/CD45R0(+)/CD27(-)) for both angioimmunoblastic T-cell lymphoma (AILT) and anaplastic large cell lymphoma (ALCL), but different cytotoxic and activation markers expressed by these tumours. A subset of CD4(+) PTCL-not otherwise specified (PTCL-NOS) may correspond to a central memory cell phenotype (CD45RA(-)/CD45R0(+)/CD27(+)). Thus, a correlation of PTCL to stages of differentiation, rather than to the direction of differentiation, may reveal homogeneous categories. A comparison between the lymphomas and their normal counterparts may contribute to the understanding of the underlying transformation mechanisms.

Nodal peripheral T-cell lymphomas and, in particular, their lymphoepithelioid (Lennert?s) variant are often derived from CD8+ cytotoxic T-cells

Nodal peripheral T-cell lymphomas are not well understood, and most of them are classified in the "not otherwise specified group" (PTCL-NOS). Data on their normal cellular derivation are ambiguous. Most peripheral T-cell lymphomas are composed of tumor cells and a (sometimes dominant) reactive background, which also includes resting and activated T-lymphocytes. We defined the phenotype of the tumor cells in 101 PTCL-NOS based on their cytological atypia and using immunohistochemical double stains on paraffin sections with CD4/Ki67 and CD8/Ki67. The results were correlated to clinical presentation and outcome. Lineage could be defined in 98 cases (97%). Tumor cells were CD4(+) in 43 cases and CD8(+) in 38. These presented at a younger age but a higher clinical stage compared with the CD4(+) lymphomas. In 15 cases, the atypical cells were CD4(-)CD8(-); two cases were CD4(+)CD8(+). Of 17 lymphoepithelioid (Lennert's) lymphomas, 15 expressed CD8, one each was CD4(+) and CD4(-)CD8(-).

Peripheral T-cell lymphoma mimicking marginal zone B-cell lymphoma

Peripheral T-cell lymphoma (PTCL) may assume a variety of histologic and cytologic appearances. We describe eight cases of PTCL morphologically simulating marginal zone B-cell lymphoma. We reviewed PTCL cases diagnosed in our institution between 1990 and 2000 and selected eight cases for study based on the following criteria: small-cell morphology with abundant, clear cytoplasm and either marginal zone involvement by the neoplastic infiltrate in lymph node biopsies or lymphoepithelial lesions in extranodal biopsies. Histologic features and ancillary studies were reviewed. Patients included six women and two men with a median age of 53 years (range, 35 to 74 years). Six patients were diagnosed with primary nodal PTCL, and two presented with primary extranodal disease. The original diagnosis was PTCL in only four cases; three cases were diagnosed as atypical lymphoid infiltrate, and one case as benign lymphoepithelial lesion. Lymph node biopsies revealed partial effacement of the architecture with residual follicles surrounded by the neoplastic small cells. Extranodal sites included hard palate, tongue, tonsil, and submandibular glands; all but one case demonstrated lymphoepithelial lesions. Monoclonality was demonstrated in six of eight cases (rearrangement of T-cell receptor gene), and three of eight had an aberrant T-cell population by flow cytometry. The differential diagnosis of atypical lymphoid infiltrates with morphologic features of marginal zone B-cell lymphoma should include PTCL. This uncommon morphological mimicry should be recognized, because PTCL is an aggressive disease regardless of morphology and should be treated accordingly.

Peripheral T-cell lymphoma (excluding anaplastic large-cell lymphoma): results from the Non-Hodgkin's Lymphoma Classification Project

BACKGROUND

Peripheral T-cell lymphoma (PTCL) is rare in most parts of the world. Therefore, we have evaluated the 96 cases of PTCL diagnosed within the Non-Hodgkin's Lymphoma Classification Project (NHLCP) (1378 cases) for their geographical distribution, pathologic features and diagnostic reliability, as well as clinical presentation and outcome.

MATERIALS AND METHODS

Diagnoses of all cases were rendered independently by five experienced hematopathologists based on morphology only, and after introduction of the immunophenotype and clinical data. Divergent diagnoses were jointly discussed and a final consensus diagnosis was established in each case. Reliability of the diagnoses was evaluated statistically, and the clinical features and outcome were analyzed according to the consensus diagnoses.

RESULTS

Seven per cent of all non-Hodgkin's lymphoma (NHL) cases reviewed were classified as PTCL and the frequency varied from 1.5% to 18.3% in different countries. The interobserver agreement with the consensus diagnosis of PTCL was 86% in the Revised European-American Lymphoma (REAL) classification, but the designation of subtypes was less reliable. Diagnostic reliability improved from 41% to 86% after immunophenotyping, but did not improve further with the addition of detailed clinical data. Clinically, angiocentric nasal lymphoma presented in young females (median age 49 years) at extranodal sites, but with few adverse risk factors, whereas angioimmunoblastic lymphoma presented most often in older males (median age 65 years) at nodal and extranodal sites with numerous risk factors. The 5-year overall and failure-free survivals for patients with PTCL treated with doxorubicin (Adriamycin)-containing regimens were only 26% and 20%, respectively. Both failure-free and overall survival were strongly correlated with the performance status and International Prognostic Index scores at presentation, but differences in survival were not observed between the major histological types. However, within the PTCL 'not otherwise specified' category, but not angioimmunoblastic lymphoma, the number of transformed blasts was prognostically relevant.

CONCLUSIONS

PTCLs can be diagnosed reliably by experienced hematopathologists, but immunophenotyping is absolutely necessary. Currently, all types of PTCL should be considered high-grade lymphomas. An increased ability to distinguish T-lymphocyte subsets is needed in order to better subclassify the PTCLs for therapeutic and prognostic purposes.

The new World Health Organization classification of lymphomas: the past, the present and the future

The REAL Classification of lymphomas, proposed in 1994, represents a new paradigm in lymphoma classification, consisting of a list of biologic entities defined by clinicopathologic and immunogenetic features. The non-Hodgkin's lymphomas comprise precursor lymphoblastic and mature cell neoplasms of B, T or putative natural killer cell lineage. An individual entity can exhibit a range of morphologic appearances and a range of clinical behavior. The categories in Hodgkin's lymphomas are identical to the widely used Rye classification except for the additional of a new category termed 'lymphocyte-rich classical Hodgkin's lymphoma'. The REAL classification has been validated by a major multi-institutional study involving 1378 cases (The Non-Hodgkin's Lymphoma Classification Project), showing that it is both reproducible and clinically relevant. The new World Health Organization classification of hematopoietic and lymphoid tumors, to be published in 2001, is a joint project of the Society for Hematopathology and European Association of Hematopathologists, under the auspices of the World Health Organization. This classification includes not only lymphoid neoplasms, but also myeloid, histiocytic and mast cell neoplasms. The lymphoma component of the classification is merely an update of the REAL classification, with minor changes necessitated by new information that has become available since its proposal. A conceptual grouping of the non-Hodgkin's lymphomas into four categories (indolent, aggressive, highly aggressive, and localized indolent) is also presented in this review. The next major impetus influencing the approach to lymphoma classification will no doubt be molecular genetics, in particular DNA microarrays, which will yield an enormous amount of new data that will aid in the understanding of lymphomas.

Systemic anaplastic large-cell lymphoma: results from the non-Hodgkin's lymphoma classification project

Anaplastic large-cell lymphoma (ALCL) is a heterogeneous process that may have a T-cell, B-cell, or indeterminant (null) phenotype and which may or may not express the anaplastic lymphoma kinase (ALK) oncoprotein. Because the clinical significance of these variants of ALCL is unclear, we evaluated the cases of ALCL-T/null and ALCL-B identified in the Non-Hodgkin's Lymphoma Classification Project. We evaluated 1,378 cases of non-Hodgkin's lymphoma (NHL), and a consensus diagnosis of ALCL-T/null was made in 33 patients (2.4%) with a diagnostic accuracy of 85%. Compared to 96 patients with other forms of peripheral T-cell lymphoma (PTCL), those with ALCL-T/null were significantly younger, less likely to have advanced-stage disease or bone marrow involvement, more likely to have a low International Prognostic Index score, and had a significantly better survival. Among those with ALCL-T/null, there were no significant differences in the clinical features or survival on the basis of ALK expression. A consensus diagnosis of ALCL-B was made in 15 patients (1.1%), and the diagnostic accuracy was 67%. However, compared to 366 patients with other forms of diffuse large B-cell lymphoma (DLBCL), those with ALCL-B were no different with regard to clinical features or survival. We conclude that patients with ALCL-T/null have favorable prognostic features and excellent survival and should be separated from those with other forms of PTCL for prognostic and therapeutic purposes. In contrast, patients with ALCL-B appear to be similar to those with other forms of DLBCL.

Fine-needle aspiration biopsy of peripheral T-cell lymphomas. A cytologic and immunophenotypic study of 33 cases

INTRODUCTION

Peripheral T-cell lymphoma (PTCL) accounts for 10-20% of all non-Hodgkin lymphomas in the United States. In this study, the authors reviewed the cytologic and immunophenotypic findings of 33 fine-needle aspirations (FNAs) of PTCL.

METHODS

Thirty-three FNAs from 26 patients (12 females and 14 males) with PTCL were identified during 1991-1999. The patients' age ranged from 19 to 96 years. Immunophenotyping was performed in 24 cases by using either flow cytometry (FC; 21 cases) or immunocytochemistry (IC; 3 cases). Follow-up included review of prior or current histology and clinical records.

RESULTS

Nine cases were associated with mycosis fungoides, three cases were classified as T-cell chronic lymphocytic leukemia, and two were angioimmunoblastic adenopathy (AILD)-like T-cell lymphoma. The remaining 19 were classified as PTCL, not otherwise specified. The latter consisted of eight mixed cell variant, eight large cell variant, and three anaplastic variant. One of the mixed cell variant and one of the large cell variants contained numerous epithelioid histiocytes (Lennert lymphoma). Thirty (91%) cases had a definitive diagnosis of malignant lymphoma. Twenty-two cases (2 IC and 20 FC) showed a predominant population of T lymphocytes without a monoclonal B-cell population. In addition, FC revealed an aberrant expression of T-cell markers in 13 cases. Two cases were interpreted as "atypical lymphoid population"; one case was an AILD-like T-cell lymphoma, and the other case was PTCL, large cell type. One case initially was interpreted as granulomatous lymphadenitis; subsequent biopsy revealed PTCL, Lennert type.

CONCLUSIONS

Peripheral T-cell lymphoma is a heterogeneous group of lesions with diverse cytomorphology. Cytologic analysis and immunophenotyping is an accurate method of diagnosing peripheral T-cell lymphoma.

Peripheral T/NK-cell lymphoma: a report of the IXth Workshop of the European Association for Haematopathology

AIMS

In April 1998, The European Association for Haematopathology organized the IXth workshop on peripheral T-cell and NK-cell lymphomas and leukaemias. The workshop focused on unusual subtypes of these rare malignancies, allowing evaluation of the recently published WHO classification of neoplastic diseases of the lymphoid tissues.

METHODS AND RESULTS

One-hundred and three cases were centrally immunophenotyped and hybridized for EBER1/2 of Epstein--Barr virus. All cases were reviewed by a panel of experienced haematopathologists and classified according to the new WHO classification for lymphoid neoplasms. Three cases were considered as precursor T-cell and 95 cases as peripheral T/NK-cell lymphoma/leukaemia. Although the cases represented a selected series of unusual cases, the following conclusions could be made: (i) Most lymphomas except the hepatosplenic gamma/delta T-cell lymphomas showed a rather broad morphological spectrum, with differences both between and within individual tumours. (ii) This heterogeneity was also reflected by the immunophenotype, for instance a variable expression of CD30 was found in many enteropathy type T-cell lymphomas. (iii) Exceptions in phenotype were regularly found in almost all categories, indicating that phenotype should not be the final determining factor in classification. (iv) The great majority of T-cell lymphomas expressed the alpha/beta T-cell receptor, with the exception of all but one hepatosplenic T-cell lymphomas and a few other extranodal peripheral T cell lymphomas. (v) Malignancies of precursor cells, blastic NK-cell lymphoma/leukaemia, adult T-cell lymphoma/leukaemia and most AIL-type T-cell lymphomas did not express cytotoxic molecules such as TIA1 and granzyme-B. In contrast, all five aggressive NK/T-cell lymphomas/leukaemias, a single case of large granular lymphocyte leukaemia and 40 of 47 primary extranodal lymphoma/leukaemias expressed these molecules. In hepatosplenic gamma/delta T-cell lymphoma, five of six cases showed expression of TIA1 but not of granzyme-B. (vi) Seven tumours developed after organ-transplant, four cases being EBV-positive. No distinct phenotype could be attributed to these cases.

CONCLUSIONS

Most peripheral T/NK cell lymphomas could be categorized as distinct entities as described in the recently proposed WHO classification for lymphoid neoplasms.

Lymphoma classification--from controversy to consensus: the R.E.A.L. and WHO Classification of lymphoid neoplasms

BACKGROUND

Controversy in lymphoma classification dates back to the first attempts to formulate such classifications. Over the years, much of this controversy arose from the assumption that there had to be a single guiding principle--a 'gold standard'--for classification, and from the existence of multiple different classifications.

DESIGN

The International Lymphoma Study Group (I.L.S.G.) developed a consensus list of lymphoid neoplasms, which was published in 1994 as the 'Revised European-American Classification of Lymphoid Neoplasms' (R.E.A.L.). The classification is based on the principle that a classification is a list of 'real' disease entities, which are defined by a combination of morphology, immunophenotype, genetic features, and clinical features. The relative importance of each of these features varies among diseases, and there is no one 'gold standard'. In some tumors morphology is paramount, in others it is immunophenotype, a specific genetic abnormality, or clinical features. An international study of 1300 patients, supported by the San Salvatore Foundation, was conducted to determine whether the R.E.A.L. Classification could be used by expert pathologists and had clinical relevance. Since 1995, the European Association of Pathologists (EAHP) and the Society for Hematopathology (SH) have been developing a new World Health Organization (WHO) Classification of hematologic malignancies, using an updated R.E.A.L. Classification for lymphomas and applying the principles of the R.E.A.L. Classification to myeloid and histiocytic neoplasms. A Clinical Advisory Committee (CAC) was formed to ensure that the WHO Classification will be useful to clinicians.

RESULTS

The International Lymphoma Study showed that the R.E.A.L. Classification could be used by pathologists, with inter-observer reproducibility better than for other classifications (> 85%). Immunophenotyping was helpful in some diagnoses, but not required for many others. New entities not specifically recognized in the Working Formulation accounted for 27% of the cases. Diseases that would have been lumped together as 'low grade' or 'intermediate/high grade' in the Working Formulation showed marked differences in survival, confirming that they need to be treated as distinct entities. Clinical features such as the International Prognostic Index were also important in determining patient outcome. The WHO Clinical Advisory Committee concluded that clinical groupings of lymphoid neoplasms was neither necessary nor desirable. Patient treatment is determined by the specific type of lymphoma, with the addition of grade within the tumor type, if applicable, and clinical prognostic factors such as the International Prognostic Index (IPI).

CONCLUSIONS

The experience of developing the WHO Classification has produced a new and existing degree of cooperation and communication between oncologists and pathologists from around the world, which should facilitate progress in the understanding and treatment of hematologic malignancies.

Peripheral T-cell lymphoma with distinct perifollicular growth pattern: a distinct subtype of T-cell lymphoma?

Nine cases of peripheral T-cell lymphoma were identified in this study showing a distinctive growth pattern with partial distortion of the lymph node structure and prominent infiltration predominantly of marginal zones by medium-sized cells with clear cytoplasm and significant nuclear atypia. In the paracortical T-zone, there was a marked proliferation of high endothelial venules. Plasmocytosis and capsular fibrosis were other distinctive features. On immunohistochemistry, the lymphomas proved to be of T-helper cell origin (CD3+, CD4+, CD5+/-, CD8-, TIA1-) and proliferation was most prominent in the marginal zone of the regressive B-cell follicles. These cases have a characteristic morphology that may be sufficient to differentiate them as a variant from other peripheral T-cell lymphomas of the "not otherwise specified" group and to include them in the list of currently recognized lymphomas. Because of the distinct perifollicular growth pattern and incomplete effacement of the lymph node architecture, the differential diagnosis consists mainly of marginal zone B-cell lymphoma and reactive lesions.

Characteristic proliferations of reticular and dendritic cells in angioimmunoblastic lymphoma

Angioimmunoblastic lymphoma (AIL) is a T-cell proliferation with a distinct clinical presentation that often poses a difficult diagnostic challenge. Angioimmunoblastic lymphoma is characterized by prominent vascular and stromal proliferations. Using a panel of antibodies, we investigated the nature of the stromal component in 15 cases of AIL as compared with 40 cases of nodal-based peripheral T-cell lymphoma (PTCL) of other types. As has been previously noted, extrafollicular proliferations of follicular dendritic cells (detected by CD21 and low molecular-weight nerve growth factor receptor staining) were highly associated with AIL and were only rarely seen in other lesions. Unexpectedly, large networks of desmin-positive reticulum cells also were noted in all cases of AIL evaluated. These cells with characteristic long cytoplasmic processes were present in much smaller numbers or only rarely in other types of peripheral T-cell lymphoma. This population of nodal stromal cells, a subset of the fibroblastic reticulum cells detected by vimentin immunostaining, may be responsible for the prominent reticulum deposition seen in AIL. No association of AIL with proliferations of other types of reticulum cells (e.g., interdigitating dendritic cells or histiocytes) was noted. These findings suggest that networks of follicular dendritic and desmin-positive reticulum cells are useful diagnostic features in angioimmunoblastic lymphoma and probably are related to the pathogenesis of this entity.

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.

The Revised European-American Classification of Lymphoid Neoplasms (REAL): a new perspective for the classification of cutaneous lymphomas

Differing classification schemes for malignant lymphomas have been used in Europe and the United States. Attempts to translate between the principle classifications have been unsuccessful and historically it has been difficult to arrive at an unified approach. In addition, many new lymphoma entities have been recognized in recent years that are not delineated in any of the existing classification schemes. To provide a unified international basis for clinical and investigative work in this field, in 1994 the International Lymphoma Study Group (ILSG) proposed a new classification termed Revised European-American Classification of Lymphoid Neoplasms (REAL). This review discusses the REAL classification, especially as it pertains to cutaneous lymphomas, and provides insight into the clinicopathologic features of lymphoproliferative disease involving the skin. The premise of the REAL classification is that a classification scheme should be based on the delineation of disease entities, utilizing pathologic, immunophenotypic, genetic, and clinical features. Therefore, if cutaneous involvement is an integral aspect of any lymphoma subtype, this clinical information is included in the definition of that neoplasm. We conclude that the principles of the REAL classification are applicable to cutaneous lymphomas, as well as lymphomas involving other anatomic sites.

Evaluation of the Revised European-American Lymphoma Classification Confirms the Clinical Relevance of Immunophenotype in 560 Cases of Aggressive Non-Hodgkin's Lymphoma

The Revised European-American Lymphoma (REAL) classification has been criticized for its emphasis on the unproven clinical relevance of immunophenotype. A worse prognosis for peripheral T-cell non-Hodgkin's lymphomas (PTCLs) has been inconsistently reported in part because the definition of PTCL has been imprecise (eg, T-cell–rich B-cell non-Hodgkin's lymphomas [TCRBCLs] have been misdiagnosed as PTCLs in the past) and because its correlation with other known prognostic factors has not been studied by multivariate analysis. We analyzed six protocols from 1984 to 1995 with Working Formulation intermediate grade and immunoblastic lymphomas (exclusive of mantle cell) and selected only those cases in which immunophenotyping was performed and was conclusive. Of a total of 560 evaluable patients, 68 were PTCLs (12%) and the remaining 492 (88%) were B-cell non-Hodgkin's lymphomas, including 16 TCRBCLs (3% of total). The 5-year failure-free survival (FFS) for PTCLs and B-cell large-cell lymphomas (BCLCLs) is 38% and 55%, respectively (P < .0001) and the 5-year overall survival (OS) is 39% and 262%, respectively (P < .001). The M.D. Anderson prognostic tumor score (MDATS) and International Prognostic Index (IPI) for all patients was calculated. With MDATS of less than 3 (good prognosis), the 5-year FFS for PTCL and BCLCL is 56% and 69%, respectively (P = .01), and the 5-year OS is 64% and 77%, respectively (P = .06). With MDATS of greater than 2 (poor prognosis), 5-year FFS for PTCL and BCLCL is 26% and 38%, respectively (P = .03), and the 5-year OS is 24% and 41%, respectively (P = .02). With an IPI of less than 3 (good prognosis), the 5-year FFS for PTCL and BCLCL is 49% and 64%, respectively (P = .001), and the 5-year OS is 55% and 71%, respectively (P = .013). With an IPI greater than 2 (poor prognosis), the 5-year FFS for PTCL and BCLCL is 11% and 35%, respectively (P = .044), and the 5-year OS is 10% and 40%, respectively (P = .011). Multivariate analysis shows that MDATS, IPI, and T-cell phenotype are totally independent and are the most significant predictors of FFS and OS. The 68 PTCLs include 45 PTCLs unspecified, 10 Ki-1 anaplastic (ALCL), 8 angioimmunoblastic, and 5 angiocentric lymphomas. Angiocentrics were usually refractory (1 of 5 remissions only). ALCL rarely relapsed late. We conclude that the immunophenotypic basis of the REAL classification is clinically relevant and that, although other prognostic features also influence outcome, the T-cell phenotype still remains an independent and significant prognostic factor.

Diagnostic value and reproducibility of fine-needle aspiration cytology in canine malignant lymphoma

Cytological examination of biopsy samples obtained by fine-needle aspiration appears to be an accurate and reliable basis for the classification of canine non-Hodgkin's lymphoma (NHL). Intra- and inter-observer reproducibility of both the original and the updated Kiel classification were assessed blindly on two occasions by two experienced cytologists who examined biopsy specimens from 78 dogs with NHL. Analysis by kappa statistics showed moderate to good intra-observer reproducibility and poor to moderate inter-observer reproducibility for the original Kiel classification. In the updated Kiel classification both intra- and inter-observer reproducibilities were good, probably due in part to the additional information provided by the immunotyping. The consensus cytological classifications were compared with those based on histology, and the association constant (Cramér's V) was 0.65 for the original Kiel classification and 0.70 for the updated Kiel classification. The results suggest that the updated Kiel classification in particular is suited to cytological classification of canine NHL.

Observer variation in histological classification of cutaneous malignant melanoma

To evaluate the variations within and between observers in the interpretation of important histological prognostic factors, a series of 96 melanoma patients was randomly selected from a database of 1691 patients with cutaneous malignant melanoma. The stained sections were examined on two occasions by four experienced pathologists. Analysis by observed agreement and kappa statistics showed maximal tumour thickness to be the best reproducible variable, with ulceration the second best. Regression was the least reproducible, with level of invasion and type of melanoma in the mid range. Intra-observer variation was uniformly less than inter-observer variation for each variable. For tumour thickness a variance component analysis was done to quantify the variability further. The clinician should not base his choice of treatment entirely on the microscopic classification but take into consideration the clinical course and appearance of the tumour.

The histopathological diagnosis of malignant mesothelioma v. pulmonary adenocarcinoma: reproducibility of the histopathological diagnosis

In a randomized design we examined the interobserver variation in the histopathological diagnosis of adenocarcinoma of the lung and malignant mesothelioma. In three rounds, three pathologists assessed slides from 42 tumours originally diagnosed as adenocarcinomas, malignant mesotheliomas or benign lesions in the pleura. In the first round the assessments were made on haematoxylin and eosin (H & E) stained sections; in the second, on H & E sections plus sections stained with histochemical mucin stains; and in the final round, the diagnoses were made on H & E sections and sections stained with a panel of antibodies against various antigens (cytokeratin, EMA, CEA, Ber-EP4, B72.3, Leu-M1, vimentin and S-100 protein) said to be of value in the differential diagnosis. The overall interobserver agreements for the three rounds were 0.659, 0.802 and 0.817; the kappa values were 0.461, 0.681 and 0.690. It is concluded that differentiation between adenocarcinoma of the lung and malignant mesothelioma should be made on sections stained with H & E and mucin and/or immunohistochemical staining reactions, including antibodies against B72.3, Ber-EP4 and CEA.

Classification of primary cutaneous T-cell lymphomas

The term cutaneous T-cell lymphoma designates a group of neoplasms of skin homing T-cells that show considerable variation in clinical presentation, histological appearances, immunophenotype and prognosis. The disadvantages of currently available histological classification schemes are discussed and a new classification is presented. This is based on a combination of clinical, histological and immunophenotypic criteria and it recognizes distinct clinico-pathological entities within this group of diseases.

High frequency of Epstein-Barr virus in Chinese peripheral T-cell lymphoma

Forty-two cases of Chinese T-cell lymphoma were studied for expression of Epstein-Barr virus (EBV) encoded RNA (EBER-1) and EBV latent membrane protein-1 (LMP-1) using in situ hybridization and immunohistochemistry, respectively. EBV was detected in tumour cells in 24/39 peripheral T-cell lymphomas (62%), comprising 18/27 pleomorphic, medium and large cell lymphomas (67%), 4/6 angioimmunoblastic lymphadenopathy-like lymphomas (67%), 2/2 Lennert's lymphomas, 0/2 anaplastic large cell lymphomas, and 0/2 T-zone lymphomas. EBV was not found in three T-lymphoblastic lymphomas. EBV was associated with 12/24 nodal (50%) compared with 12/15 extranodal (80%) peripheral T-cell lymphomas. In EBV positive nodal lymphomas, 9/12 cases (75%) contained less than 10% EBER positive tumour cells. In EBV positive extranodal lymphomas, 9/11 cases (82%) showed EBV gene expression in more than 50% of the tumour cells, and in five of these almost all tumour cells were positive. Lymphomas of the nasopharynx (mainly midline granuloma-type) showed EBER-1 expression in nearly all tumour cells. LMP-1 was detected in 19/23 EBER positive peripheral T-cell lymphomas (83%). Our results show that EBV is strongly associated with peripheral T-cell lymphomas in Chinese. An important role for the virus is suggested in lymphomas of the nasopharynx. The significance of EBV in T-cell lymphomas that contain only a minor population of virally infected tumour cells is currently unclear.

Relation of CD30 expression to survival and morphology in large cell B cell lymphomas

AIMS

To investigate whether CD30 expression is correlated with anaplastic morphology, and whether this correlated with a better survival in large cell B cell lymphomas, as has been described for T cell lymphomas.

METHODS

CD30 expression was investigated using frozen sections in a series of 146 large cell B cell lymphomas. Clinical data and follow up information were collected from 25 lymphomas with strong CD30 expression, 30 lymphomas with partial CD30 expression, and a control group of 25 lymphomas which did not express CD30.

RESULTS

Morphological distinction between anaplastic and non-anaplastic tumours was difficult. Of the cases with an anaplastic morphology, 50% were CD30 positive, as were 24% of the polymorphic centroblastic B cell lymphomas. Only 65% of the morphologically non-anaplastic tumours were completely CD30 negative. There was no difference in survival among patients with lymphomas expressing CD30 and those that did not. Patients with morphologically anaplastic B cell lymphomas did not differ in their survivals from those with other high grade B cell lymphomas. Clinical stage at presentation was the only variable that was significantly associated with survival.

CONCLUSIONS

CD30 expression occurs frequently in large cell B cell lymphomas and is poorly related to anaplastic morphology. Morphological distinction between anaplastic and non-anaplastic tumours is difficult. In contrast to T cell lymphomas, CD30 positive B cell lymphomas do not show a relatively favourable clinical course. The results presented here raise serious doubts as to whether large cell B cell lymphoma, based on the expression of CD30 or anaplastic morphology, can really be termed a separate entity.

Usefulness of follicular dendritic cell pattern in classification of peripheral T-cell lymphomas

Classification of peripheral T-cell lymphomas based on morphological criteria can present problems due to overlap in histological features amongst the subtypes. An immunohistochemical study was designed to study the follicular dendritic cell patterns in 21 cases of peripheral T-cell lymphoma which had been classified using the updated Kiel classification. Three patterns of distribution were observed: 1 follicular dendritic cells not detected (3 cases); 2 follicular dendritic cells restricted to remnant follicle centres (7); 3 follicular dendritic cells present as an expanded network of cells exceeding the confines of germinal centres (11). Ten out of 11 angioimmunoblastic lymphomas showed an expanded network of follicular dendritic cells. The only negative case showed features which, on review, were in keeping with a pleomorphic, medium and large cell lymphoma showing an unusual proliferation of small venules. Other than angioimmunoblastic lymphomas, only one other case showed follicular dendritic cell hyperplasia. This was an unclassified peripheral T-cell lymphoma. We conclude that follicular dendritic cell hyperplasia may be used an an aid to diagnosis of the angioimmunoblastic type of peripheral T-cell lymphoma, and we recommend the routine staining of these cells in typing of T-cell lymphomas to facilitate comparison between centres.

Clinicopathologic study of 212 cases of peripheral T-cell lymphoma among the Japanese

BACKGROUND

Postthymic/peripheral T-cell malignancy shows significant histopathologic and clinical diversity, even in its prognosis, and the correlations remain to be debated.

METHODS

The clinicopathologic features of 212 Japanese patients with these neoplasms were investigated.

RESULTS

There were 131 male and 81 female patients, whose ages ranged from 2 to 90 years (mean, 51.7 years). Lymphadenopathy was the most frequent clinical presentation, and the patients also had frequent skin lesions, hyperimmunoglobulinemia, hypercalcemia, and a rapid clinical course. Furthermore, the differences in the histologic features of each subcategory reflected the clinical pictures. The immunophenotypic analysis was indispensable in establishing a correct diagnosis, and the high-grade tumors often showed loss of pan-T antigens.

CONCLUSIONS

The histopathologic classification proposed by Suchi et al., which has been incorporated into the updated Kiel classification, showed a good prognostic correlation.

Noncutaneous T-cell lymphomas. Recognition of a lymphoma type (large cell anaplastic) with a relatively favorable prognosis

BACKGROUND

The clinical relevance of the updated Kiel classification for T-cell lymphomas is discussed. Large series with long-term follow-up are needed to investigate the clinical relevance of a separation into high- and low-grade T-cell lymphomas, based on the Kiel classification.

METHODS

The clinicopathologic data of 97 consecutive noncutaneous T-cell lymphomas, diagnosed in the Comprehensive Cancer Center Amsterdam, between July 1, 1985, and December 1, 1990, were reviewed and analyzed for their prognostic significance.

RESULTS

Immunohistochemistry contributed substantially in the diagnosis of T-cell lymphoma. Using the updated Kiel classification, many difficulties occurred in classifying these lymphomas. Only large cell anaplastic lymphoma (LCAL) and lymphoblastic lymphoma (LBL) were classified with a high degree of confidence. Variables associated with prolonged survival were classified as LCAL and low stage of disease (Stage I and II) at clinical presentation. Multivariate survival analysis revealed that subtype (grouped as LCAL versus non-LCAL) was selected as the most significant variable, closely followed by stage of disease at clinical presentation (grouped as Stage I/II versus Stage III/IV). LCAL was associated with a significantly better survival than were all other types of high-grade T-cell lymphoma (P = 0.018) and tended to be associated with a better survival than low-grade T-cell lymphoma (P = 0.067). No significant differences in survival were found between the other types of T-cell lymphoma or between high- and low-grade T-cell lymphomas as classified according to the updated Kiel classification. Other variables, such as sex and age (younger than 60 years versus older than 60 years) had no significant influence on survival time.

CONCLUSIONS

This study indicates that the clinical relevance of classifying primary noncutaneous T-cell lymphomas according to the updated Kiel classification is limited because only a diagnosis of LCAL has prognostic relevance in predicting survival.

Peripheral T-cell lymphoma: a clinicopathological study of 41 cases and evaluation of the prognostic significance of the updated Kiel classification

A total of 41 non-cutaneous peripheral T-cell lymphomas were classified following the updated Kiel classification. Of these, 20 cases belonged to the low-grade group (T-cell chronic lymphocytic leukaemia, 3; lymphoepithelioid, 5; angioimmunoblastic, 4; pleomorphic small cell, 8) and 21 to the high grade group (pleomorphic medium and large cell, 11; immunoblastic, 3; large-cell anaplastic Ki-1 positive, 7). Seventy per cent showed a CD4+/CD8-phenotype, 39% a defective phenotype and 88% an activation phenotype. Eighty per cent had B-symptoms, 63% hepatomegaly, 48% splenomegaly and 26% had involvement of more than three lymphoid areas. Bone marrow was infiltrated in 34%, central nervous system in 4%, lung in 12% and skin in 14.6%. Seventeen per cent presented with extranodal disease and 82.8% had stage III/IV disease. Hypergammaglobulinaemia was found in 29%, hypercalcaemia in 7%, raised LDH serum levels in 58% and HTLV-I antibodies in only one case. Of the 37 treated patients 18 (48%) achieved a complete remission, but 33% relapsed. Mortality was 59% and actuarial overall survival at 38 months was 0.32. In the comparison of the clinical, analytical and immunophenotypic variables and outcome between low and high grade groups, only the average of bone marrow infiltration in the low grade and stage I-II, presence of defective phenotypes and higher Ki-67 positivity in the high grade group were significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

T-cell lymphoma in Singapore: pathology, clinical findings and association with HTLV-1 antibodies

Of 128 cases of malignant lymphomas studied in Singapore between 1986 and 1988, 28 were identified as peripheral T-cell lymphomas. Sera from two of the 128 cases were positive for HTLV-1 antibodies and both cases had the clinical and pathological features of adult T-cell leukaemia/lymphoma. The pathological and clinical features of the 28 cases of peripheral T-cell lymphoma are presented in detail. Survival data indicated no significant difference between the low grade and high grade histological types. Three of the patients had previous or concomitant malignancies. The percentage of T-cell lymphomas associated with HTLV-1 infection in Singapore is low compared to those areas in which HTLV-1 is endemic.