A revision of the nearly 8-year-old World Health Organization classification of the lymphoid neoplasms and the accompanying monograph is being published. It reflects a consensus among ...hematopathologists, geneticists, and clinicians regarding both updates to current entities as well as the addition of a limited number of new provisional entities. The revision clarifies the diagnosis and management of lesions at the very early stages of lymphomagenesis, refines the diagnostic criteria for some entities, details the expanding genetic/molecular landscape of numerous lymphoid neoplasms and their clinical correlates, and refers to investigations leading to more targeted therapeutic strategies. The major changes are reviewed with an emphasis on the most important advances in our understanding that impact our diagnostic approach, clinical expectations, and therapeutic strategies for the lymphoid neoplasms.
Waldenström's macroglobulinemia is a lymphoplasmacytic lymphoma. Genetic analysis has revealed a common mutation (L265P) in
MYD88
in more than 90% of patients with this disease. The mutation appears ...to activate NF-κB.
Waldenström's macroglobulinemia is an IgM-secreting lymphoplasmacytic lymphoma (LPL).
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Clinical manifestations of Waldenström's macroglobulinemia include cytopenia resulting from bone marrow infiltration by lymphoplasmacytic cells, paraprotein-related cryoglobulinemia, the cold agglutinin syndrome, demyelinating neuropathy, and symptomatic hyperviscosity.
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The oncogenic basis of Waldenström's macroglobulinemia has not been defined. Familial clustering of Waldenström's macroglobulinemia and other B-cell disorders suggests that genetic factors play a role in the pathogenesis of Waldenström's macroglobulinemia in certain patients.
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IgM monoclonal gammopathy of unknown significance (MGUS) is characterized by the presence of a monoclonal IgM protein and the absence of bone marrow disease involvement on histologic examination.
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IgM . . .
Developing countries are required to produce robust estimates of forest carbon stocks for successful implementation of climate change mitigation policies related to reducing emissions from ...deforestation and degradation (REDD). Here we present a "benchmark" map of biomass carbon stocks over 2.5 billion ha of forests on three continents, encompassing all tropical forests, for the early 2000s, which will be invaluable for REDD assessments at both project and national scales. We mapped the total carbon stock in live biomass (above- and belowground), using a combination of data from 4,079 in situ inventory plots and satellite light detection and ranging (Lidar) samples of forest structure to estimate carbon storage, plus optical and microwave imagery (1-km resolution) to extrapolate over the landscape. The total biomass carbon stock of forests in the study region is estimated to be 247 Gt C, with 193 Gt C stored aboveground and 54 Gt C stored belowground in roots. Forests in Latin America, sub-Saharan Africa, and Southeast Asia accounted for 49%, 25%, and 26% of the total stock, respectively. By analyzing the errors propagated through the estimation process, uncertainty at the pixel level (100 ha) ranged from ±6% to ±53%, but was constrained at the typical project (10,000 ha) and national (>1,000,000 ha) scales at ca. ±5% and ca. ±1%, respectively. The benchmark map illustrates regional patterns and provides methodologically comparable estimates of carbon stocks for 75 developing countries where previous assessments were either poor or incomplete.
The International Peripheral T-Cell Lymphoma Project is a collaborative effort designed to gain better understanding of peripheral T-cell and natural killer (NK)/T-cell lymphomas (PTCLs). A total of ...22 institutions in North America, Europe, and Asia submitted clinical and pathologic information on PTCLs diagnosed and treated at their respective centers. Of the 1314 eligible patients, 181 had anaplastic large-cell lymphoma (ALCL; 13.8%) on consensus review: One hundred fifty-nine had systemic ALCL (12.1%) and 22 had primary cutaneous ALCL (1.7%). Patients with anaplastic lymphoma kinase–positive (ALK+) ALCL had a superior outcome compared with those with ALK− ALCL (5-year failure-free survival FFS, 60% vs 36%; P = .015; 5-year overall survival OS, 70% vs 49%; P = .016). However, contrary to prior reports, the 5-year FFS (36% vs 20%; P = .012) and OS (49% vs 32%; P = .032) were superior for ALK− ALCL compared with PTCL, not otherwise specified (PTCL-NOS). Patients with primary cutaneous ALCL had a very favorable 5-year OS (90%), but with a propensity to relapse (5-year FFS, 55%). In summary, ALK− ALCL should continue to be separated from both ALK+ ALCL and PTCL-NOS. Although the prognosis of ALK− ALCL appears to be better than that for PTCL-NOS, it is still unsatisfactory and better therapies are needed. Primary cutaneous ALCL is associated with an indolent course.
The International Peripheral T-cell Lymphoma Project is a collaborative effort to better understand peripheral T-cell lymphoma (PTCL). A total of 22 institutions submitted clinical and pathologic ...material on 1314 cases. One objective was to analyze the clinical and pathologic features of 340 cases of PTCL, not otherwise specified. The median age of the patients was 60 years, and the majority (69%) presented with advanced stage disease. Most patients (87%) presented with nodal disease, but extranodal disease was present in 62%. The 5-year overall survival was 32%, and the 5-year failure-free survival was only 20%. The majority of patients (80%) were treated with combination chemotherapy that included an anthracycline, but there was no survival advantage. The International Prognostic Index (IPI) was predictive of both overall survival and failure-free survival (P < .001). Multivariate analysis of clinical and pathologic prognostic factors, respectively, when controlling for the IPI, identified bulky disease (≥ 10 cm), thrombocytopenia (< 150 × 109/L), and a high number of transformed tumor cells (> 70%) as adverse predictors of survival, but only the latter was significant in final analysis. Thus, the IPI and a single pathologic feature could be used to stratify patients with PTCL-not otherwise specified for novel and risk-adapted therapies.
B-cell lymphomas with concurrent IGH-BCL2 and MYC rearrangements, also known as "double-hit" lymphomas (DHL), are rare neoplasms characterized by highly aggressive clinical behavior, complex ...karyotypes, and a spectrum of pathologic features overlapping with Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL) and B-lymphoblastic lymphoma/leukemia (B-LBL). The clinical and pathologic spectrum of this rare entity, including comparison to other high-grade B-cell neoplasms, has not been well defined. We conducted a retrospective analysis of clinical and pathologic features of 20 cases of DHL seen at our institution during a 5-year period. In addition, we carried out case-control comparisons of DHL with BL and International Prognostic Index (IPI)-matched DLBCL. The 11 men and 9 women had a median age of 63.5 years (range 32 to 91). Six patients had a history of grade 1 to 2 follicular lymphoma; review of the prior biopsy specimens in 2 of 5 cases revealed blastoid morphology. Eighteen patients had Ann Arbor stage 3 or 4 disease and all had elevated serum lactate dehydrogenase (LDH) levels at presentation. Extranodal disease was present in 17/20 (85%), bone marrow involvement in 10/17 (59%) and central nervous system (CNS) disease in 5/11 (45%). Nineteen patients were treated with combination chemotherapy, of whom 18 received rituximab and 14 received CNS-directed therapy. Fourteen patients (70%) died within 8 months of diagnosis. Median overall survival in the DHL group (4.5 mo) was inferior to both BL (P=0.002) and IPI-matched DLBCL (P=0.04) control patients. Twelve DHL cases (60%) were classified as B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and BL, 7 cases (35%) as DLBCL, not otherwise specified, and 1 case as B-LBL. Distinguishing features from BL included expression of Bcl2 (P<0.0001), Mum1/IRF4 (P=0.006), Ki-67 <95% (P<0.0001), and absence of EBV-EBER (P=0.006). DHL commonly contained the t(8;22) rather than the t(8;14) seen in most BL controls (P=0.001), and exhibited a higher number of chromosomal aberrations (P=0.0009). DHL is a high-grade B-cell neoplasm with a poor prognosis, resistance to multiagent chemotherapy, and clinical and pathologic features distinct from other high-grade B-cell neoplasms. Familiarity with the morphologic and immunophenotypic spectrum of DHL is important in directing testing to detect concurrent IGH-BCL2 and MYC rearrangements when a karyotype is unavailable. The aggressive clinical behavior and combination of genetic abnormalities seen in these cases may warrant categorization as a separate entity in future classifications and call for novel therapeutic approaches.
Cyclin D1-positive B cells are occasionally found in the mantle zones of reactive lymphoid follicles, a condition that has been called "in situ mantle cell lymphoma". The clinical significance of ...this lesion remains uncertain.
The clinical and pathological characteristics, including SOX11 expression, of 23 cases initially diagnosed as in situ mantle cell lymphoma were studied.
Seventeen of the 23 cases fulfilled the criteria for in situ mantle cell lymphoma. In most cases, the lesions were incidental findings in reactive lymph nodes. The t(11;14) was detected in all eight cases examined. SOX11 was positive in seven of 16 cases (44%). Five cases were associated with other small B-cell lymphomas. In two cases, both SOX11-positive, the in situ mantle cell lymphoma lesions were discovered after the diagnosis of overt lymphoma; one 4 years earlier, and one 3 years later. Twelve of the remaining 15 patients had a follow-up of at least 1 year (median 2 years; range, 1-19.5), of whom 11 showed no evidence of progression, including seven who were not treated. Only one of 12 patients with an in situ mantle cell lymphoma lesion and no diagnosis of mantle cell lymphoma at the time developed an overt lymphoma, 4 years later; this case was also SOX11-positive. The six remaining cases were diagnosed as mantle cell lymphoma with a mantle zone pattern. Five were SOX11-positive and four of them were associated with lymphoma without a mantle zone pattern.
In situ mantle cell lymphoma lesions are usually an incidental finding with a very indolent behavior. These cases must be distinguished from mantle cell lymphoma with a mantle zone pattern and overt mantle cell lymphoma because they may not require therapeutic intervention.
Follicular lymphoma (FL), a common nodal lymphoma, is rare in the gastrointestinal (GI) tract. We report our experience with primary FL of the GI tract.
The surgical pathology computer files at the ...Massachusetts General Hospital were searched for cases of FL involving the GI tract. Patients were included if on staging, the major site of disease was the GI tract. Thirty-nine cases were identified. Clinical data were collected from electronic medical records.
The 27 women and 12 men ranged in age from 29 to 79 years (median, 59 y). Thirty tumors involved the small bowel (19 the duodenum); 8 involved the colon; and 1 involved the stomach. Eight of 10 tumors that were resected involved the small bowel (jejunum and/or ileum without duodenum) of which 5 presented with intestinal obstruction. All tumors were grade 1 or 2. Immunostains showed consistent expression of CD20 (100%), CD10 (97%), and Bcl-2 (97%). Among the 34 cases with Ann Arbor staging information, 22 were stage I, 10 were stage II, and 2 were (6%) stage IV. Of 36 cases with follow-up (median, 4.5 y), 27 patients are alive without disease, 7 are alive with disease, and 2 died of other causes. No lymphoma-related deaths were recorded.
Primary FL of the GI tract occurs most often in middle-aged adults with a 2:1 female preponderance. The most frequent site of involvement is the duodenum, followed by the ileum and colon. Distal small bowel involvement is more likely to present as bowel obstruction requiring resection. The disease is localized in the bowel and regional lymph nodes in the vast majority of cases. The prognosis is favorable even when the disease is disseminated.
Primary cutaneous lymphomas are currently classified by the European Organization for Research and Treatment of Cancer (EORTC) classification or the World Health Organization (WHO) classification, ...but both systems have shortcomings. In particular, differences in the classification of cutaneous T-cell lymphomas other than mycosis fungoides, Sézary syndrome, and the group of primary cutaneous CD30+ lymphoproliferative disorders and the classification and terminology of different types of cutaneous B-cell lymphomas have resulted in considerable debate and confusion. During recent consensus meetings representatives of both systems reached agreement on a new classification, which is now called the WHO-EORTC classification. In this paper we describe the characteristic features of the different primary cutaneous lymphomas and other hematologic neoplasms frequently presenting in the skin, and discuss differences with the previous classification schemes. In addition, the relative frequency and survival data of 1905 patients with primary cutaneous lymphomas derived from Dutch and Austrian registries for primary cutaneous lymphomas are presented to illustrate the clinical significance of this new classification.
Recently the World Health Organization (WHO), in collaboration with the European Association for Haematopathology and the Society for Hematopathology, published a revised and updated edition of the ...WHO Classification of Tumors of the Hematopoietic and Lymphoid Tissues. The 4th edition of the WHO classification incorporates new information that has emerged from scientific and clinical studies in the interval since the publication of the 3rd edition in 2001, and includes new criteria for the recognition of some previously described neoplasms as well as clarification and refinement of the defining criteria for others. It also adds entities—some defined principally by genetic features—that have only recently been characterized. In this paper, the classification of myeloid neoplasms and acute leukemia is highlighted with the aim of familiarizing hematologists, clinical scientists, and hematopathologists not only with the major changes in the classification but also with the rationale for those changes.
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