Mantle cell lymphoma: recent insights into pathogenesis, clinical variability, and new diagnostic markers

Mantle cell lymphoma (MCL; previously called centrocytic lymphoma or lymphocytic lymphoma of intermediate differentiation) is a distinct subtype of B-cell lymphoma, accounting for approximately 3%-10% of all lymphoma diagnoses. The name refers to the growth pattern in early disease presentation resembling the normal mantle zone that surrounds the germinal center of the B-cell follicle. The hallmark of MCL is the t(11;14)(q13;q32), resulting in aberrant expression of the CCND1 gene and expression of cyclin D1 in the tumor cells. Expression and genomic profiling of MCL have provided new insight into the pathogenesis and will be summarized in this review. Pitfalls in the differential diagnosis versus B-cell chronic lymphocytic leukemia, B-cell prolymphocytic leukemia, cyclin D1-positive diffuse large B-cell lymphoma, hairy cell leukemia, and plasma cell tumors will be discussed, including the usefulness new diagnostic markers SOX11 and CD200. In situ MCL, MCL with an indolent clinical course, and cyclin D1-negative MCL are other topics of this review.     

逆转录聚合酶链反应检测石蜡包埋组织中细胞周期蛋白D1 mRNA对套细胞淋巴瘤的诊断价值

目的 探讨用逆转录聚合酶链反应（RT-PCR）法和竞争性RT-PCR法检测套细胞淋巴瘤（MCL）石蜡包埋组织中细胞周期蛋白D1（cyclin D1）蛋白和mRNA在常规病理工作中的可行性及其诊断和鉴别诊断价值。方法 收集淋巴结内MCL38例、对照组包括结内小B细胞淋巴瘤58例（B小淋巴细胞性淋巴瘤14例,淋巴浆细胞性淋巴瘤3例,滤泡性淋巴34例,淋巴结边缘区B细胞淋巴瘤7例）和淋巴结反应性增生病例20例,用免疫组织化学EnVision法和RT-PCR法、竞争性RT-PCR法检测cyclin D1蛋白及其mRNA的表达,以看家基因PGK作为内对照检测RNA。结果 （1）38例结内MCL中,cyclin D1蛋白阳性率为71．1％（27／38）,对照组均为阴性。（2）116例标本中,可检出内对照PGK基因mRNA表达103例（88．8％）。38例MCL中PGK阳性36例（94．7％）。（3）38例结内MCL中,34例可检出cyclin D1 mRNA表达,去除PGK和cyclin D1 mRNA均阴性的2例,MCL中cyclin D1 mRNA表达的阳性率为94．4％（34／36）。对照组中B小淋巴细胞性淋巴瘤1例检出cyclin D1 mRNA表达,其余病例均未检出cyclin D1 mRNA表达。PCR结果全部经测序证实。（4）用竞争性RT-PCR,38例结内MCL中27例可检出cyclin D1 mRNA高表达,去除2例PGK也为阴性的病例,MCL中cyclin D1 mRNA高表达率为75．0％（27／36）。对照组小B细胞恶性淋巴瘤及淋巴结反应性增生无1例有cyclin D1 mRNA高表达。结论 RT-PCR方法和竞争性RT-PCR方法可在石蜡包埋组织中检测cyclin D1 mRNA的表达,均可用于MCL的诊断。     

CD5-positive mucosa-associated lymphoid tissue (MALT) lymphoma of ocular adnexal origin: usefulness of fluorescence in situ hybridization for distinction between mantle cell lymphoma and MALT lymphoma

Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type (MALT lymphoma) usually lacks CD5 expression. Herein is described two cases of CD5-positive MALT lymphoma of ocular adnexal origin. The differential diagnosis between CD5-positive MALT lymphoma and mantle cell lymphoma (MCL), notably cyclin D1-negative MCL, was difficult because both cases consisted histologically of small to medium-sized cells with diffuse or vaguely nodular growth pattern, and the neoplastic cells were positive for CD5 and negative for cyclin D1. Somatic mutation analysis of the immunoglobulin heavy chain variable region (VH) gene in case 1 found a relatively higher mutation frequency (5.0%), which was not definitive to rule out MCL. Interphase fluorescence in situ hybridization (FISH) on paraffin-embedded section using IgH/cyclin D1 (CCND1) probe showed that in both cases there was no molecular evidence of t(11;14), finally leading to the diagnosis of CD5-positive MALT lymphoma. Although the present two patients had no recurrence over 34 months after initial diagnosis, careful observation is needed because the clinicopathological significance of MALT lymphoma with this rare phenotype remains obscure.     

Prominent intrasinusoidal infiltration of the bone marrow by mantle cell lymphoma

Intrasinusoidal infiltration of bone marrow (BM) may accompany several malignant lymphoproliferative disorders. In small B-cell lymphomas, this pattern is considered specific for splenic marginal zone lymphoma (SMZL) when exclusive or prominent, although it may occur in other subtypes of non-Hodgkin's lymphomas (NHLs) as a minor feature. Here we report 2 cases of mantle cell lymphoma (MCL) with a prominent intrasinusoidal BM infiltration pattern. Both patients presented with massive splenomegaly and peripheral blood involvement characterized by markedly atypical lymphocytes, but no lymphadenopathy. The cytological features and the phenotype of the lymphoma cells were diagnostic of MCL. The malignant B cells showed coexpression of B-cell markers (CD20+ and CD79a+), CD5 antigen, and cyclin D1 by immunohistochemistry. We discuss the specificity of an intrasinusoidal growth pattern in the bone marrow, emphasizing the importance of using a broader immunohistochemical panel in the differential diagnosis of intrasinusoidal BM infiltration by NHL.     

原发淋巴结套细胞淋巴瘤临床病理分析

目的：探讨原发淋巴结套细胞淋巴瘤（MCL）的临床病理与免疫组化特点。方法：收集6例淋巴结MCL,免疫组化ABC法确定肿瘤细胞特征,使用的抗体有CD45、CD20、CD79、CD45RO、CD30、CD68、TdT、CD43、CD5、cyclinD1、c-myc,IgD,IgM等。结果：光镜可将MCL分为4种亚型：套区型1例,结节型1例,弥漫型2例,母细胞化型2例。肿瘤细胞表达全B细胞标记,IgD CD43 ,cyclinD1(5/6),CD5(4/6) 。结论：MCL是一种具有特殊免疫表型的B细胞淋巴瘤,不同的组织学构型其预后可能不同,临床应与其它类型B细胞淋巴瘤鉴别,如淋巴结边缘区B细胞淋巴瘤（MZL）,滤泡性淋巴瘤（FL）及CLL／SLL等鉴别。     

Early lymph node involvement by mantle cell lymphoma limited to the germinal center: report of a case with a novel "follicular in situ" growth pattern

Recently, several reports have described cases of "in situ" mantle cell lymphoma (MCL) in which scattered cyclin D1+ cells were present within the mantle zones of reactive-appearing lymphoid follicles. In this report, we describe an unusual histologic pattern of in situ MCL that was identified in a staging lymph node for colonic adenocarcinoma resected 4 years before a diagnosis of symptomatic MCL. Retrospective immunohistochemical studies showed scattered cyclin D1-expressing cells within otherwise reactive germinal centers but not in the surrounding mantle zones. The presence of early MCL cells limited to reactive germinal centers represents a novel "follicular in situ" growth pattern for MCL, which overlaps morphologically with reactive follicular hyperplasia and follicular lymphoma and which could have implications for MCL pathogenesis.     

套细胞淋巴瘤的临床病理特征和细胞周期蛋白D1在诊断中的意义

目的 观察套细胞淋巴瘤的临床病理学特征及细胞周期蛋白D1染色在诊断中的意义。方法 对8例淋巴结套细胞淋巴瘤作临床病理观察及随访,LSAB法做免疫表型分析（CD45RO、CD5、CD20、细胞周期蛋白D1、Ki-67、bcl-2）。结果 患者年龄43-78岁（平均年龄57岁）,男女3：1。组织学特点为：（1）淋巴结结构破坏并被单一的淋巴样细胞所取代,淋巴细胞以套区增生性、结节性、弥漫性三种模式增生。（2）淋巴样细胞核有一定的不规则性,染色质中等致密,核分裂象少见,类似中心细胞。其中有3例转变为高度侵袭性的母细胞样变型。所有的病例都呈cyclinD1与bcl-2阳性、CD20阳性、CD45RO阴性、CD5阳性。结论 套细胞淋巴瘤有其特征的形态改变及免疫表型。根据组织病理学特征及cyclin D1阳性,可与其它类型的小B细胞淋巴瘤相鉴别。套细胞淋巴瘤的母细胞样变型也应当与其它变型区别。     

Expression of transmembrane adaptor protein PAG/Cbp in diffuse large B-cell lymphoma: immunohistochemical study of 73 cases

PAG/Cbp is a transmembrane adaptor protein involved in proximal immune signaling. It is expressed in reactive germinal centers (GC) of secondary lymphatic follicles and related malignant lymphomas. We studied PAG/Cbp expression in GC-like and non-GC-like diffuse large B-cell lymphoma (DLBCL) subtypes. Seventy-three cases of DLBCL identified among 155 malignant lymphomas were classified as GC-like DLBCL (CD10+ or CD10-, bcl-6+, and MUM1-) and non-GC-like DLBCL (CD10-, MUM1+ or CD10-, bcl-6+, MUM1+). PAG/Cbp was detected by monoclonal antibody MEM-255 following routine immunohistochemical procedures. Thirty-five of 40 GC-like DLBCLs (88%) and 20 of 33 non-GC-like DLBCL cases (61%) expressed PAG/Cbp. Four of 12 bcl-6-negative non-GC-like DLBCL cases (33%) were PAG/Cbp positive, and only 4 of 20 bcl-6-positive non-GC-like DLBCL cases (25%) were PAG/CBP negative. All 37 FL and all 5 Burkitt's lymphomas (BL) expressed PAG/Cbp, whereas all 6 mantle cell lymphomas (MCL) and 4 of 5 chronic lymphocytic leukemias (CLL/SLL) were PAG/Cbp negative. PAG/Cbp is a reliable GC marker. Its expression correlates with GC-like DLBC phenotype in a significant majority of cases. It is typically absent in MCL and SLL/CLL.     

Cytokeratin expression in hematological neoplasms: a tissue microarray study on 866 lymphoma and leukemia cases

Aberrant expression of cytokeratins (CK) is known to occasionally occur in malignant lymphomas. The monoclonal mouse-anti-human CK cocktail CK22 recognizes keratin polypeptides with a wide range of molecular weights and can be applied in diagnostic panels for tumors of unknown origin. Using tissue microarray technology, we tested 1059 lymphoma and acute leukemia cases, covering the most common disease entities, for aberrant CK expression, using CK22. In total, 866 of the arrayed cases were evaluable (80%), and 13 positive cases (1.5%) were found: 1 out of 230 Hodgkin lymphomas (0.4%), 1 plasma cell myeloma, 2 out of 326 diffuse large B-cell lymphomas (0.6%), 5 out of 18 mantle cell lymphomas (26%), 3 out of 70 small cell lymphomas/chronic lymphocytic leukemias (4%) and 1 out of 27 peripheral T-cell lymphomas, not otherwise specified (4%). Immunostaining was finely granular in most cases, and the total amount of positively staining cells exceeded 10% only in the cases of Hodgkin lymphoma and plasmocytoma. All CK22-positive cases, except for one mantle cell lymphoma, expressed the specific simple epithelial CK8 but not the basal/stratified epithelial CK5/6. Aberrant CK expression can be encountered in a small subset of otherwise characteristic B- and T-cell lymphomas, but not in acute leukemias, which should be considered in difficult differential diagnostic settings.     

SOX11 is useful in differentiating cyclin D1‐positive diffuse large B‐cell lymphoma from mantle cell lymphoma

Hsiao S‐C, Cortada I R, Colomo L, Ye H, Liu H, Kuo S‐Y, Lin S‐H, Chang S‐T, Kuo T U, Campo E & Chuang S‐S
(2012) Histopathology  61, 685–693 SOX11 is useful in differentiating cyclin D1‐positive diffuse large B‐cell lymphoma from mantle cell lymphoma Aims: To characterize the frequency and clinicopathological features of cyclin D1‐positive diffuse large B‐cell lymphoma (DLBCL) and the usefulness of SOX11 in the differential diagnosis from mantle cell lymphoma (MCL). Methods and results: We retrospectively stained 206 consecutive DLBCLs for cyclin D1, and identified three (1.5%) positive cases, comprising two in the elderly with necrosis, and a third with a starry‐sky pattern. All three cases shared the same non‐germinal centre B‐cell (non‐GCB) phenotype [CD5?/CD10?/bcl‐6+/MUM1+/SOX11?], Epstein–Barr virus (EBV) negativity, and absence of CCND1 aberrations by fluorescence in‐situ hybridization. The third case showed both BCL6 and MYC rearrangements: a double‐hit lymphoma. In the same period there were 22 MCLs, all expressing cyclin D1, with 89% cases expressing SOX11, a frequency that is statistically different from cyclin D1‐positive DLBCL. Notably, we identified a pleomorphic MCL initially misdiagnosed as DLBCL. A separate cohort of 98 DLBCL cases was negative for SOX11, with only one case expressing cyclin D1 with a GCB phenotype (CD10+/bcl‐6+/MUM1?). The two patients with tumour necrosis rapidly died of disease. The other two were in complete remission after immunochemotherapy. Conclusions: Cyclin D1‐positive DLBCLs are rare, and they are negative for SOX11 or CCND1 aberration. SOX11 is useful in differentiating cyclin D1‐positive DLBCL from MCL.     

bcl-1 REARRANGEMENT AND CYCLIN D1 PROTEIN EXPRESSION IN MANTLE CELL LYMPHOMA

Centrocytic lymphoma, or mantle cell lymphoma (MCL), is characterized by a chromosomal translocation t(11;14) (q13;q32) involving the bcl-1 locus on chromosome 11. Cyclin D1 is a cell-cycle regulatory protein essential for G1–S transition and has been identified as a potential transforming gene affected by the translocation. In this study, 32 cases of MCL were analysed for the bcl-1 rearrangement and cyclin D1 protein expression. In 17 cases, a rearrangement at the major translocation cluster of bcl-1 could be detected. Twenty-four cases exhibited nuclear cyclin D1 expression that was not detectable in other B-cell lymphomas ( n =40) or in normal B-cells. In nine MCL samples, cyclin D1 was expressed without a detectable bcl-1 rearrangement. The detection of a t(11;14) by means of classical cytogenetics in one of these cases, however, may suggest that this discrepancy could be due to chromosomal breakages outside the typical translocation cluster region. In two cases, a bcl-1 rearrangement was not accompanied by cyclin D1 expression. This study provides further evidence that cyclin D1 is involved in the pathogenesis of MCL and can be exploited as a diagnostic marker in the differential diagnosis of B-cell lymphomas and in the identification of MCL.     

套细胞淋巴瘤石蜡包埋组织中细胞周期蛋白D1和t(11;14)易位检测的临床病理意义

目的 探讨套细胞淋巴瘤石蜡包埋组织中细胞周期蛋白(cyclin)D1和t(11;14)易位检测的可行性及其诊断和鉴别诊断价值。方法 收集套细胞淋巴瘤36例,对照组小B细胞恶性淋巴瘤71例,均为石蜡包埋组织,运用免疫组织化学方法观察cyclin D1的表达;用半巢式聚合酶链反应(PCR)法检测t(11;14)易位,以看家基因β-肌动蛋白(actin)作为内对照检测DNA质量。结果 (1)36例套细胞淋巴瘤中26例(72．2％)表达cyclin D1,对照组无1例表达。(2)107例标本中101例(94．4％)可检出β-actin DNA表达。36例套细胞淋巴瘤中22例检出t(11;14)易位,对照组无1例检出。去除B-actin和t(11;14)易位均阴性2例,套细胞淋巴瘤中t(11;14)易位检出率为64．7％。(3)36例套细胞淋巴瘤中cyclin D1染色和(或)t(11;14)易位检测阳性病例为29例,总阳性率为80．5％。结论套细胞淋巴瘤石蜡包埋组织中cyclin D1和t(11;14)易位的检测具较高的特异性和可行性,两者的综合应用有助于正确的诊断和鉴别诊断。     

De novo CD5+ diffuse large B-cell lymphomas. A heterogeneous group containing an unusual form of splenic lymphoma

We reviewed our institutional experience with de novo CD5+, large B-cell lymphomas to determine whether they represent a distinct entity and are related to CD5+ small B-cell disorders. We identified 13 cases with multiparameter flow cytometry over a period of 58 months (5% of large B-cell lymphomas) in 7 females and 6 males. Three groups were identified. Group 1 (2 cases) had diffuse splenic red pulp involvement with a distinctive cordal pattern of infiltration, no other clinical evidence of mass disease, microscopic disseminated disease on further workup, and an identical immunoglobulin-negative immunophenotype. Group 2 cases (7 cases) were clinically and morphologically heterogeneous and had an immunophenotype resembling mantle cell lymphoma (FMC7-positive, CD23-). Group 3 (4 cases) had miscellaneous immunophenotypes, including one closely resembling chronic lymphocytic leukemia. Cyclin D1 was positive in only 1 of 10 evaluable cases (group 2). We conclude that CD5+ diffuse large B-cell lymphomas are heterogeneous; most cases do not seem to be related to chronic lymphocytic leukemia or mantle cell lymphoma. However, we identified a subgroup of primary splenic CD5+ large B-cell lymphoma with diffuse red pulp involvement and believe this may represent a distinct clinicopathologic entity.     

Lymphomatous polyposis of the gastrointestinal tract, including mantle cell lymphoma, follicular lymphoma and mucosa-associated lymphoid tissue lymphoma

AIMS: Lymphomatous polyposis (LP) is considered to represent mantle cell lymphoma (MCL) of the gastrointestinal (GI) tract. However, a few reports have suggested that some are follicular lymphoma (FL) or mucosa-associated lymphoid tissue (MALT) lymphomas. In this study, we analysed 35 patients and clarified the clinicopathological features of LP. METHODS AND RESULTS: Paraffin-embedded tissue samples were stained immunohistochemically and analysed by tissue-fluorescence in situ hybridization (T-FISH) for IGH/CCND1 (cyclin D1) and IGH/BCL2. The average age of the patients was 58.3 years. Over half of the cases showed gastric, duodenal, small intestinal, ileocaecal and sigmoid colonic lesions (15, 19, 15, 16 and 16 cases, respectively). Phenotypically, cases were classified into three types of MCL (cyclin D1+ CD5+ CD10-) (n=12), FL (cyclin D1- CD5- CD10+) (n=14) and MALT (cyclin D1- CD5- CD10-) (n=9). T-FISH identified 11 of the 11 examined cases with MCLs to have IGH/CCND1, while seven of 10 cases with FL had IGH/BCL2, and none of the MALT cases were positive for IGH/CCND1 or IGH/BCL2. At the study endpoint, five of 12 patients with MCL were dead, two of 14 with FL and one of nine with MALT were dead of other disease. Event-free survival analysis showed significantly poorest outcome in MCL, followed by FL, while MALT was associated with a favourable outcome (P=0.0040). CONCLUSIONS: Our study emphasizes the importance of differentiating MCL, FL and MALT of LP in evaluating prognosis and hence the most suitable therapeutic regimen.     

p27(Kip1) immunostaining for the differential diagnosis of small b-cell neoplasms in trephine bone marrow biopsies.

The distinction between mantle cell lymphoma (MCL) and other small B-cell non-Hodgkin lymphomas (NHL) is important because MCL has a more aggressive clinical course. In bone marrow (BM) biopsy specimens, this distinction can be particularly difficult. Although cyclin D1 immunostaining and molecular detection of the t(11;14) translocation are highly specific markers for MCL, they fail to detect a proportion of cases. We have recently described that MCL typically lacks detectable expression of the cyclin-dependent kinase inhibitor p27(kip1) protein by immunostaining, which is expressed at high levels in most small B-cell NHL inversely correlated to the proliferation rate. We therefore examined whether p27(kip1) immunostaining could be a useful adjunct for the differential diagnosis of small B-cell NHL infiltrates in the BM. Trephine BM biopsy specimens of 96 patients, including well-characterized MCL (19 cases), B-cell chronic lymphocytic leukemia (27 cases), follicular lymphoma (18 cases), hairy cell leukemia (22 cases), and marginal zone lymphoma (10 cases) as well as 10 reactive BM, including five with benign lymphoid aggregates were investigated. In addition, the presence of a t(11;14) translocation involving the major translocation cluster was studied by PCR in all MCL. All cases of B-cell chronic lymphocytic leukemia, follicular lymphoma, and marginal zone lymphoma revealed a strong p27(kip1) nuclear staining in the majority of neoplastic cells. Fourteen (78%) cases of MCL were p27(kip1)-negative in the tumor cells, whereas four cases revealed a weak nuclear positivity. Seventeen (77%) cases of hairy cell leukemia were also either completely negative for p27(kip1) or showed a faint positive staining in a minority of the neoplastic cells. Nine of 19 cases (47%) of MCL showed a bcl1 rearrangement involving the major translocation cluster region. These findings demonstrate that p27(kip1) immunostaining is a valuable additional marker for the differential diagnosis of small B-cell NHL infiltrates in BM biopsies. The reduction or lack of p27(kip1) protein expression in MCL, as well as in hairy cell leukemia, might be an important event in the pathogenesis of these disorders.     

Immunostaining for cyclin D1 and the diagnosis of mantle cell lymphoma: is there a reliable method?

Immunostaining for cyclin D1 has become essential for the reliable diagnosis of mantle cell lymphoma (MCL). MCL is associated with a poor prognosis and its distinction from other small B-cell lymphomas is clinically important. However, many diagnostic laboratories report problems in finding a reliable method. The following articles by Chan and by Miller, Munson & Isaacson discuss the common problems and describe successful methods with advice on diagnostic interpretation.     

Immunohistochemical detection of cyclin D1 using optimized conditions is highly specific for mantle cell lymphoma and hairy cell leukemia.

Mantle cell lymphoma (MCL) is more aggressive when compared with other lymphomas composed of small, mature B lymphocytes. Cyclin D1 is overexpressed in MCL as a result of the translocation t(11;14)(q13;q32). Cyclin D1 immunohistochemistry in fixed, paraffin-embedded tissue contributes to the precise and reproducible diagnosis of MCL without the requirement of fresh tissue. However, its use in bone marrow biopsies is not well established. In addition, increased levels of cyclin D1 mRNA have been found in hairy cell leukemia but have not consistently been detected by immunohistochemistry. We used a polyclonal antibody and heat-induced antigen retrieval conditions to evaluate 73 fixed, paraffin-embedded bone marrow, spleen, and lymph node specimens with small B-cell infiltrates, obtained from 55 patients. Cyclin D1 was overexpressed in 13/13 specimens of MCL (usually strong, diffuse reactivity in most tumor cells) and in 14/14 specimens of hairy cell leukemia (usually weak, in a subpopulation of tumor cells). No reactivity was detected in five cases of B-chronic lymphocytic leukemia; five cases of splenic marginal zone lymphoma; six cases of nodal marginal zone cell lymphoma; two cases of gastric marginal zone cell lymphoma; or ten benign lymphoid infiltrates in bone marrow, spleen, or lymph nodes. In summary, although the total number of studied cases is small and a larger series of cases may be required to confirm our data, we present optimized immunohistochemical conditions for cyclin D1 in fixed, paraffin-embedded tissue that can be useful in distinguishing MCL and hairy cell leukemia from other small B-cell neoplasms and reactive lymphoid infiltrates.