T-immunoblastic lymphoma mimicking B-immunoblastic lymphoma

A T-cell immunoblastic lymphoma having plasmacytoid features that mimic B-cell immunoblastic lymphoma, is described. The lesion was composed of sheets of pleomorphic plasmacytoid cells that displayed a helper T-cell immunophenotype (Leu-1+, Leu-3+, Leu-4+, Leu-5+, Leu-9-, Leu-2-). Ultrastructural features were consistent with a T-cell lymphoma. Flow cytometric analysis revealed that the cells were DNA triploid and had a high proliferative activity. Although the histology of immunoblastic lymphomas alone may suggest either a T- or B-cell phenotype, immunophenotyping is essential in making this distinction.     

肝脾γδT和αβT细胞淋巴瘤

从 1990年Ｆａｒｃｅｔ等描述了 2例肝脾γδＴ细胞淋巴瘤以来 ,人们渐渐认识到肝脾γδＴ细胞淋巴瘤是一个独立的淋巴瘤亚类 ,1994年它被ＲＥＡＬ分类确认为一个临时的淋巴瘤亚类[1] ;而在新的ＷＨＯ血液和淋巴组织肿瘤分类中它被确认为一个独立的疾病[1] 。它有典型的临床病理特征 ,包括多为青年男子发病 ,有Ｂ症状 (发热、夜汗、体重减轻 ) ,肝脾肿大 ,没有淋巴结病 ,重度贫血 ,明显的血小板减少症。患者多在诊断后 1年内死亡。组织学上 ,主要为小到中等大小的肿瘤细胞浸润脾脏的脾索和脾窦 ,以及肝窦 ,骨髓血窦等。特征性的免疫表型为Ｃ…     

Discordant lymphoma: MALT lymphoma of the stomach and follicular lymphoma of the parotid gland

More than one histological type of malignant lymphoma can occur simultaneously in an individual. The entity is classified as either composite or discordant lymphoma. Both types of lymphoma, particularly discordant lymphoma comprised of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue lymphoma (MALT-L) and follicular lymphoma (FL), are rare. We report a case of discordant lymphoma comprising MALT-L in the stomach and FL in the parotid gland. The patient was a 50-year-old Japanese woman who visited the University Hospital of Showa (Tokyo, Japan) because a barium study showed erosive gastric lesions. A gastro-intestinal endoscopy was performed 2 months after the barium study, which showed irregular erosions throughout the stomach body. A gastric biopsy showed MALT-L, and Helicobacter pylori (H. pylori) infection was confirmed. The patient had noticed a painless and elastic hard tumor mass of about 2 cm in diameter in the area of the left parotid gland 6 months before the barium study. We removed the parotid gland tumor and diagnosed it as FL 6 months after the barium study. We were able to diagnose the MALT-L and FL by morphological, immunohistochemical and molecular analyses of paraffin-embedded sections. This appears to be the first reported case of MALT-L and FL occurring together as a discordant lymphoma.     

Mediastinal lymphoma

Malignant lymphoma may involve the mediastinum as a component of disseminated disease or as a primary lesion. The most common types of primary mediastinal lymphomas (ML) are Hodgkin's disease (HD, usually of the nodular sclerosis type), large cell lymphoma (often associated with sclerosis), and lymphoblastic lymphoma (frequently seen in conjunction with acute lymphoblastic leukemia). The characteristic clinical, morphologic, and immunophenotypic features of these three neoplasms are reviewed. ML must be distinguished from Castleman's disease, an enigmatic lymphoid proliferation that frequently involves the mediastinum.     

Mantle cell lymphoma disguised as marginal zone lymphoma

We report a case of mantle cell lymphoma histologically indistinguishable from marginal zone lymphoma. An 83-year-old man presented with a 9.0-cm, slowly enlarging axillary mass. Microscopically, the neoplastic process was largely interfollicular, surrounding residual follicular centers, some of which had discernible small lymphocyte mantles. Overall, the morphologic pattern was highly suggestive of marginal zone lymphoma. However, flow cytometric and immunohistochemical results, including cyclin D1 positivity, revealed an immunophenotype that fit with mantle cell lymphoma. The differential diagnosis of mantle cell lymphoma is broad, and it is well known that mantle cell lymphoma can assume a number of histologic appearances, including, infrequently, that of more indolent B-cell non-Hodgkin lymphomas. Although not pathognomonic, cyclin D1 positivity is highly specific for mantle cell lymphoma and is key in distinguishing these clinically dissimilar malignant lymphomas. In recent years, detection of cyclin D1 has expanded the recognizable histologic spectrum of mantle cell lymphoma.     

Differential expression of Toll-like receptors in follicular lymphoma,diffuse large B-cell lymphoma and peripheral T-cell lymphoma

Although Toll-like receptors (TLRs) in mammals are well-known to play important roles in innate immunity, newer roles for the TLRs have suggested that cells with aberrant TLR expression may have a survival advantage over normal cells. Lymphocytes are one of a small number of cell types that express many of the TLRs, suggesting that abnormal TLR levels/signaling may potentially influence the progression of malignant lymphomas. Thus, frozen samples of 51 lymph nodes from patients with follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL) and peripheral T-cell lymphoma (PTCL) were analyzed for the expression of TLR1 to 9 using quantitative real-time PCR, and compared to those in reactive lymphadenopathy (RL) samples. TLR2 was over-expressed in both DLBCL and PTCL but not in FL when compared to RL. TLR1 and TLR4 expression was up-regulated in PTCL, while TLR8 was highly expressed in DLBCL. Although TLR5 showed lower expression in FL, expression of TLR3, TLR6, TLR7 and TLR9 did not vary significantly between different lymphoma subtypes. Double immunostaining revealed an increase in the number of TLR2 and/or TLR8 expressing lymphoma cells in DLBCL. In PTCL, TLR2 and TLR4 expression was localized to neoplastic T cells. TLR expression is highly variable among lymphoma subtypes. However, despite this some significant differences exist that may prove useful in the development of novel therapeutic strategies.     

Oral solid form of primary effusion lymphoma mimicking plasmablastic lymphoma

Primary effusion lymphoma (PEL) is a rare large cell lymphoma subtype that usually is associated with human immunodeficiency virus infection. Features facilitating PEL identification are its clinical presentation, cytologic findings, immunophenotypic profile, and particularly, relation to human herpesvirus 8 (HHV8) infection. Uncommonly, PEL may present as a solid form that predominantly involves the distal digestive tract and poses major diagnostic problems, especially when unassociated with body cavity effusions. We herein report the case of an HIV-positive 42-year-old male with synchronous presentation of a pleural cavity PEL and a tongue-based lesion, both displaying plasmablastic features. Demonstration of HHV8 presence in the lingual lesion excluded a plasmablastic lymphoma and established the diagnosis of an oral solid form of PEL. This case illustrates the need for investigating HHV8 in any plasmablastic-looking lymphoma, especially in HIV-infected patients.     

Extranodal lymphoma

Lymphomas arising in extranodal sites are intriguing. The types of lymphomas encountered vary widely from one extranodal site to another. For many types of extranodal lymphomas, there are distinctive clinicopathologic features, sometimes including association with an underlying immunodeficiency syndrome, autoimmune disease, infection, or other immunologic disorder, or a predilection to affect patients of certain ethnic origins. Presented below is a review of lymphomas that are encountered most often in extranodal sites.     

Gastrointestinal lymphoma

The gastrointestinal tract is the commonest site for primary extranodal malignant lymphoma. Despite this, gastrointestinal lymphomas are rare and present diagnostic and conceptual challenges. Principal among these are the differential diagnoses of malignant lymphoma and carcinoma and malignant lymphoma and pseudolymphoma, especially in the stomach; the nature of Mediterranean lymphoma and of the lymphoma complicating celiac disease; and the conceptual basis for differentiation of follicular centre cell lymphomas in the intestine.     

A distinctive composite lymphoma consisting of clonally related mantle cell lymphoma and follicle center cell lymphoma.

Although follicle center cell lymphoma and mantle cell lymphoma are both B cell non-Hodgkin's lymphomas (NHL), they are regarded as separate entities with distinct clinical, morphological, immunophenotypic and molecular characteristics. To our knowledge, the coexistence of these 2 lymphomas in the same patient has never been reported. We describe a 70-year-old woman with a long-standing history of follicle center cell lymphoma, cytological grade I, who subsequently developed a composite lymphoma consisting of well-demarcated foci of persistent follicle center cell lymphoma surrounded by mantle cell lymphoma. This morphological interpretation was supported by the presence of both bcl-1 and bcl-2 gene rearrangements, which are molecular genetic hallmarks of mantle cell lymphoma and follicle center cell lymphoma, respectively. Polymerase chain reaction (PCR) analysis for rearranged immunoglobulin heavy chain (IgH) genes showed a dominant band identical in size in microdissected tumor cells of the follicle center cell and mantle cell lymphomas. Cloning and sequence analysis of the PCR products revealed a common clone-specific IgH gene rearrangement in these 2 lymphomas. These findings suggest that this composite lymphoma represents the unusual evolution of a malignant B-cell clone that resulted in the development of 2 morphologically distinct but clonally related B-cell NHLs. These findings also show the importance of integrating morphological, immunophenotypic, and molecular data to enhance our understanding of the complex pathogenic interrelationships in lymphomagenesis.