Lymphoma Disease Discovery and Defintion

在2008年《Blood》杂志的一篇全体文章中，我们报道了滤泡性淋巴瘤（FL）患者中出现的组织细胞/树突状细胞（H/DC）肉瘤，我们提供了证据表明H/DC肉瘤与潜在的FL具有克隆相关性，两者都携带相同的IGH基因重排和t（14:18）。我们提供的证据表明，这些肿瘤是通过转分化过程产生的，通过抑制PAX5和上调PU.1和CEBP β介导。这项研究首次证明了成熟的人b细胞在体内或体外的转分化。再加上我们之前对组织细胞树突状细胞肿瘤与急性淋巴细胞白血病（t细胞或b细胞谱系）相关的描述，我们的研究为造血系统细胞之间非凡的谱系可塑性提供了证据。在最近的研究中，我们报道了7例慢性淋巴细胞白血病/小淋巴细胞淋巴瘤伴组织细胞和树突状细胞肉瘤的形态学、分子和细胞遗传学分析。7例患者均为老年男性（中位年龄71岁）。7例患者中有6例b细胞肿瘤先于组织细胞和树突状细胞肉瘤的发展，1例患者同时诊断出这两种肿瘤。激光捕获显微解剖和PCR分析显示，在所有病例中，两种表型不同的成分中存在相同的克隆免疫球蛋白基因重排。染色体17p异常是肉瘤中最常见的细胞遗传学异常，在研究的6例病例中有5例可见。与CLL/SLL细胞相比，组织细胞/树突状细胞PAX5大部分呈阴性，但PU.1表达较强，CEBP β表达变弱。我们的研究为CLL/SLL b细胞向树突状和较少的组织细胞谱系的肿瘤的转分化提供了证据，并表明继发性遗传事件可能在这一现象中发挥作用。在实体肿瘤中，细胞的恶性转化是通过积累遗传和分子事件的多步骤过程而被广泛接受和认可的。这些概念很难应用于淋巴系统，因为淋巴系统中细胞自然循环并定植在不同的组织中。近年来，我们的研究主要集中在这些早期病变上，包括原位滤泡性淋巴瘤和最近的原位套细胞。我们在近十年前首次描述了滤泡原位淋巴瘤（FLIS），但其临床意义仍不确定。在最近发表在《Blood》杂志上的一项研究中，我们重新评估了我们的原始系列和最近诊断的病例，以制定区分FLIS和部分累及滤泡性淋巴瘤（PFL）的标准。34例FLIS被确定，大多数是偶然发现的反应性淋巴结。6/34例患者既往或并发FL， 5/34例FLIS合并另一种淋巴瘤。在诊断和随访时分期为阴性的患者（21例）中，只有1例（5%）发展为FL。17例BCL2基因重排荧光原位杂交检测均为阳性。PFL患者更容易发展为FL。FLIS可以可靠地与PFL区分开来，并且其发展为临床显著FL的比率非常低。FLIS可能代表循环t（14;18）阳性b细胞的组织对应体。我们还研究了23例最初诊断为原位套细胞淋巴瘤（MCL）的临床和病理特征，包括SOX11的表达。16例中SOX11阳性7例（44%）。5例合并其他小b细胞淋巴瘤。14例患者随访至少1年（中位3年，范围1-19.5）。SOX11表达与进展为套细胞淋巴瘤的风险高度相关。与原位滤泡性淋巴瘤一样，原位MCL病变通常是偶然发现的，表现非常懒散，可能不需要治疗干预。同样与原位滤泡性淋巴瘤相似，应区分具有套带模式的MCL和原位MCL的部分累及。我们的小组对t细胞和nk细胞肿瘤的分类有着长期的兴趣。我们之前描述了原发性皮肤γ δ t细胞淋巴瘤（TCLs），并表明它们具有侵袭性的临床病程，与大多数α β t细胞衍生的皮肤TCLs相反。2008年世卫组织分类只承认两种形式的成熟型γ δ TCL，分别是肝脾型和原发性皮肤型γ δ TCL。我们之前提出，伽马δ tcl也可能出现在其他结外部位，但对这些肿瘤的了解非常有限，只有少数病例报道。我们最近扩展了伽玛δ tcl的研究（Garcia et al., 2011）。鉴于这些肿瘤的罕见性，这项研究是一项国际合作，涉及来自美国、西班牙、法国和台湾的研究人员。表征伽马δ tcl的一个问题是缺乏可靠的标记物来检测石蜡切片中的TCR γ或δ表达。我们使用一种针对人TCR δ常数区的单克隆抗体（克隆5A6.E9）检测了TCR δ链。在一部分TCR沉默，TCR β和TCR δ均阴性的病例中，我们也采用了最近发表的抗体来检测TCR γ链。我们的数据表明，伽玛δ衍生TCL的频谱比以前所认识的更广泛，伽玛δ TCL的文献出现在其他结外或更罕见的结处。我们还注意到，具有II型EATL特征的病例似乎是γ δ t细胞起源，但仍有一部分其他肠道t细胞淋巴瘤缺乏肠病特征，具有γ δ或TCR沉默表型。对一组沉默TCLs的识别表明，TCR β表达的缺乏不能用于预测γ δ t细胞的起源。此外，gamma delta tcl和TCR沉默tcl的临床行为具有侵袭性，大多数患者的生存期不到两年。我们的小组也是第一个描述影响硬脑膜的MZLs的小组。大多数病例为女性，放射学表现类似脑膜瘤。我们注意到这些肿瘤往往出现在脑膜上皮细胞集中的部位，可能表明与其他MALT型结外MZL类似的上皮性。在最近的一项研究中，我们分析了27名女性和5名男性的32例基于硬脑膜的MZLs，年龄从33-82岁（中位50岁）。在IgG4检测亚群中，6/18原发硬膜MZL（包括1例硬膜外肿瘤）显示大量IgG4阳性浆细胞；6例中5例均为轻链限制性克隆。6例igg4阳性MZL中3例未出现细胞遗传学畸变。在所有病例中，FISH和RT-PCR在3/9的病例中发现异常（3和18三体；3和1三体；18三体），没有任何malt型特异性易位。无论采用何种治疗方式，17例随访患者中有16例在4-124个月（中位19.5个月）期间无疾病证据存活。IgG4在硬膜MZL的一个重要亚群（包括硬膜外位置的一个亚群）的轻链限制性克隆浆细胞中的表达是一个新的发现，并指出了独特的生物学。有趣的是，正如最近其他人报道的那样，这可能是一些轨道MZL共有的特征，并扩展了我们对IgG4相关疾病的理解。

Annual Report Summary 2011, Disease Discovery In a Plenary article appearing in Blood in 2008, we reported histiocytic/dendritic cell (H/DC) sarcomas arising in patients with follicular lymphoma (FL) We provided evidence that the H/DC sarcomas were clonally related to the underlying FL, both carrying the same IGH gene rearrangement, and the t(14:18). We provided evidence that these tumors arose through a process of transdiffentiation, mediated through repression of PAX5 and upregulation of PU.1 and CEBP beta. This study was the first demonstration of transdifferentiation in a mature human B-cell in an in vivo or in vitro setting. Coupled with our earlier descriptions of histiocytic dendritic cells neoplasms in association with acute lymphocytic leukemia of either T-cell or B-cell lineage, our studies provided evidence for extraordinary lineage plasticity among cells of the hematopoietic system. In more recent work we reported the morphologic, molecular and cytogenetic analysis of 7 cases of chronic lymphocytic leukemia/small lymphocytic lymphoma associated with histiocytic and dendritic cell sarcomas. All seven patients were elderly males (median age, 71 years). The B-cell neoplasms preceded the development of the histiocytic and dendritic cell sarcomas in 6 of 7 patients, and one patient had both tumors diagnosed at the same time. Laser-capture microdissection and PCR analysis showed identical clonal immunoglobulin gene rearrangements in the two phenotypically distinct components in all cases. .Chromosome 17p abnormalities were the most common cytogenetic abnormality detected in the sarcomas, seen in 5 of 6 cases studied. Compared with the CLL/SLL cells, the histiocytic/dendritic cells were largely negative for PAX5, but showed strong expression of PU.1 and variable and weak expression of CEBP beta. Our study provided evidence for transdifferentiation of CLL/SLL B-cells to tumors of dendritic and less often histiocytic lineage, and suggested that secondary genetic events may play a role in this phenomenon. The idea of malignant transformation of cells through a multistep process of accumulating genetic and molecular events is well accepted and recognized in solid tumors. These concepts have been difficult to apply in the lymphoid system where the cells naturally circulate and colonize different tissues. Our studies in recent years have focused on these early lesions, both follicular lymphoma in situ and more recently mantle cell in situ. We first described Follicular lymphoma in situ (FLIS) nearly a decade ago, but its clinical significance remains uncertain. In a study recently published in Blood, we reevaluated our original series and more recently diagnosed cases to develop criteria for the distinction of FLIS from partial involvement by follicular lymphoma (PFL). 34 cases of FLIS were identified, most often as an incidental finding in a reactive lymph node. 6/34 patients had prior or concurrent FL, and 5/34 had FLIS composite with another lymphoma. Of patients with negative staging at diagnosis and available follow-up (21 patients), only one (5%) developed FL . Fluorescence in situ hybridization for BCL2 gene rearrangement was positive in all 17 cases tested. PFL patients were more likely to develop FL. FLIS can be reliably distinguished from PFL, and has a very low rate of progression to clinically significant FL. FLIS may represent the tissue counterpart of circulating t(14;18)-positive B-cells. We also studied the clinical and pathologic characteristics, including SOX11 expression, of 23 cases initially diagnosed as mantle cell lymphoma (MCL) in situ. SOX11 was positive in 7 of 16 cases (44%). Five cases were associated with other small B-cell lymphomas. Fourteen patients had at least one year follow-up (median 3 years, range 1-19.5). SOX11 expression was highly associated with risk of progression to mantle cell lymphoma. Like follicular lymphoma in situ, in-situ MCL lesions are usuallyan incidental finding with a very indolent behavior, and may not require therapeutic intervention. Also similar to follicular lymphoma in situ, a distinction should be made between partial involvement by MCL with a mantle zone pattern and in situ MCL. Our group has had a long standing interest in the classification of T-cell and NK-cell neoplasms. We had previously characterized primary cutaneous gamma delta T-cell lymphomas (TCLs), and showed that they had an aggressive clinical course, in contrast to most cutaneous TCLs of alpha beta T-cell derivation. The 2008 WHO classification recognizes only two forms of mature gamma delta TCL, hepatosplenic and primary cutaneous gamma delta TCL, respectively. We had previously suggested that gamma delta TCLs might also arise in other extranodal sites, but knowledge of these neoplasms is very limited, with only few reported cases.We have recently expanded our work on gamma delta TCLs (Garcia et al., 2011). Given the rarity of these tumors, this study was an international collaboration involving investigators from the U.S., Spain, France and Taiwan. One problem in characterizing gamma delta TCLs is the lack of reliable markers to detect TCR gamma or delta expression in paraffin sections. We were able to detect the TCR delta chain using a primary monoclonal antibody raised against the human TCR delta constant region (clone 5A6.E9). In a subset of cases that appeared to be TCR silent, negative for both TCR beta and TCR delta, we also employed a recently published antibody to detect the TCR gamma chain. Our data indicated that the spectrum of gamma delta derived TCL is broader than previously appreciated, with the documentation of gamma delta TCL presenting in other extranodal or more rarely nodal sites. We also noted that cases with features of type II EATL appear to be of gamma delta T-cell origin, but that there is still a subset of other intestinal T-cell lymphomas lacking features of enteropathy that have either a gamma delta or TCR silent phenotype. The recognition of a group of silent TCLs indicates that the lack of TCR beta expression cannot be used to predict a gamma delta T-cell origin. Additionally, the clinical behavior of the gamma delta TCLs and TCR silent TCLs was aggressive, with survival less than two years in most patients. Our group was also the first to describe MZLs affecting the dura. Most cases are identified in women, with a radiological presentation simulating meningioma. We noted that these tumors tend to arise at sites where meningothelial cells are concentrated, possibly indicating epitheliotropism similar to other extranodal MZL of MALT type. In a recent study we analyzed 32 dura-based MZLs identified in 27 females and 5 males ranging in age from 33-82 yrs (median 50). In a subset tested for IgG4, 6/18 primary dural MZL (including one epidural tumor) showed numerous IgG4-positive plasma cells; all six were light chain restricted and clonal by PCR in 5 of 6 tested cases. Three of 6 IgG4-positive MZL did not show any cytogenetic aberrations. Across all cases, FISH and RT-PCR identified abnormalities in 3/9 cases (trisomies 3 and 18; trisomies 3 and 1; trisomy 18) without any MALT-type specific translocations. Regardless of the treatment modality, 16 of 17 patients with follow-up are alive without evidence of disease over a period of 4-124 months (median 19.5). The expression of IgG4 in light chain-restricted clonal plasma cells of a significant subset of dural MZL, including one in an epidural location, is a novel finding and points to distinctive biology. Interestingly, this may be a feature shared by some orbital MZL, as recently reported by others, and expands our understanding of IgG4 related disease.