The morphological spectrum of monocytoid B-cell lymphoma and its relationship to lymphomas of mucosa-associated lymphoid tissue

Extranodal MALT Lymphoma in the Oral Cavity: A Series of Three Cases with Review of Literature

BACKGROUND

Diagnosis of MALT lymphoma in the oral cavity is challenging. There is a great overlap in the histopathologic, immuno-histochemical and molecular features of MALT lymphoma with reactive lymphoid proliferations. The literature shows a very few case reports of primary MALT lymphoma of oral cavity.

METHODS

We discuss the histopathologic, immuno-histochemical, cytogenetic features, treatment and behavior of 3 cases of primary MALT lymphoma oral cavity along with review of literature.

RESULTS

The age ranged from 40 to 57 years (male to female ratio = 2:1). The sites involved were hard palate, bilateral gingivobuccal sulcus and right buccal mucosa. The most common histology was centrocyte-like (2 cases). Lymphoepithelial lesions were absent. On immunohistochemistry, all tumors showed diffuse strong CD20 and bcl2 expression with strong and diffuse MNDA staining in one case. IgH; MALT1 translocation was not seen in any of these cases. One patient received local radiotherapy, one received steroids; while the case 3 received RCHOP (Rituximab, cyclophosphamide, hydroxydaunorubicin hydrochloride, vincristine and prednisone) chemotherapy. Two patients had complete remission while one had recurrence.

CONCLUSION

MALT lymphoma of oral cavity shows a wide spectrum of morphology with presence of transformed cells, that may lead to misdiagnosis of DLBL. Treatment guidelines are not well established but a tendency to excise MALT lymphomas of oral cavity has been observed. Nevertheless, MALT lymphoma of oral cavity appears to be an indolent disease.

Recognizing nodal marginal zone lymphoma: recent advances and pitfalls. A systematic review

The diagnosis of nodal marginal zone lymphoma is one of the remaining problem areas in hematopathology. Because no established positive markers exist for this lymphoma, it is frequently a diagnosis of exclusion, making distinction from other low-grade B-cell lymphomas difficult or even impossible. This systematic review summarizes and discusses the current knowledge on nodal marginal zone lymphoma, including clinical features, epidemiology and etiology, histology, and cytogenetic and molecular features. In particular, recent advances in diagnostics and pathogenesis are discussed. New immunohistochemical markers have become available that could be used as positive markers for nodal marginal zone lymphoma. These markers could be used to ensure more homogeneous study groups in future research. Also, recent gene expression studies and studies describing specific gene mutations have provided clues to the pathogenesis of nodal marginal zone lymphoma, suggesting deregulation of the nuclear factor kappa B pathway. Nevertheless, nodal marginal zone lymphoma remains an enigmatic entity, requiring further study to define its pathogenesis to allow an accurate diagnosis and tailored treatment. However, recent data indicate that it is not related to splenic or extranodal lymphoma, and that it is also not related to lymphoplasmacytic lymphoma. Thus, even though the diagnosis is not always easy, it is clearly a separate entity.

A clinicopathological study of nodal marginal zone B-cell lymphoma. A report on 21 cases

AIMS

To report the clinicopathological findings of 21 cases of primary nodal marginal zone B-cell lymphoma (NMZL). NMZL is a recently characterized lymphoma and few series have been published.

METHODS AND RESULTS

The clinical data were characteristic of a disseminated disease at presentation: presence of peripheral and abdominal lymph nodes, bone marrow involvement (62%), disease stage III and IV (76%), elevated lactate dehydrogenase (LDH) (48%). Other features included peripheral blood involvement (23%), anaemia (24%), thrombocytopenia (10%) and presence of serum M component (33%), while the previously reported association with hepatitis C virus and cryoglobulinaemia was not found. Relapses were frequent but the majority of patients receiving chemotherapy had a good initial response. Morphological features were heterogeneous and there were some differences compared with other marginal zone B-cell lymphomas (MZL). Pure monocytoid B-cell lymphomas were rare (10%) but a minor component of monocytoid B cell was observed more frequently (23%). Plasmacytoid or plasmacytic differentiation was a very common feature (61%). Large cells and a high mitotic count were also frequent (57%).

CONCLUSION

NMZL can be distinguished from splenic MZL and extranodal MZL by its aggressive morphology and disseminated disease at presentation.

Prevalence and pattern of antinuclear autoantibodies in 347 patients with non-Hodgkin's lymphoma

The presence of antinuclear autoantibodies (ANA) was investigated in a large cohort of patients with non-Hodgkin's lymphoma (NHL) in order to assess their frequency, specificity and prognostic relevance. ANA were analysed in 347 patients with different histological subgroups of NHL and in 213 controls using an indirect immunofluorescence technique on HEp2 cells. As the appearance of autoantibodies may be found after treatment of NHL, samples were collected at the time of diagnosis of NHL before any therapy. Sixty-six (19%) NHL patients and 12 (5.6%) patients from the control group displayed ANA. The prevalence between the two groups was found to be significantly higher in NHL patients (P < 0.0001) with a marked increased prevalence in follicular and mantle cell lymphoma subgroups. Autoantibodies directed against mitotic proteins or mitotic-associated proteins were found in 6.9% of NHL patients versus 0.5% in the control group (P < 0.001), with a significantly increased incidence in follicular and mantle cell lymphoma subgroups (P < 0.0001). Some 28% of the patients with positive ANA displayed clinical symptoms that could correspond to classical autoimmune manifestations, this frequency appearing to be higher in the marginal zone/mucosa-associated lymphoid tissue lymphoma subgroup. These data demonstrate a significant incidence of ANA before any treatment in NHL occurrence, which seems to be higher in some histological subgroups with particular ANA, such as ANA directed against mitotic proteins or mitotic-associated proteins.

Nodal marginal zone lymphoma: a heterogeneous tumor: a comprehensive analysis of a series of 27 cases

We have reviewed the clinical, morphologic, immunophenotypical, and molecular features of a series of 27 cases of nodal marginal zone lymphoma with the aim of defining this entity more precisely. The series was characterized by a relatively favorable clinical course, with a low clinical stage at diagnosis (59% patients with clinical stage I-II) and a 5-year overall survival probability of 79%. However, the disease persisted in a relatively large fraction of the patients, thus yielding a 5-year failure-free survival probability of 22%. Molecular and immunohistochemical analyses of the series revealed heterogeneity in the frequency of IgV(H) somatic mutation and in the expression of IgD, CD43, MUM1, and CD38. Apart from the absence of nuclear Bcl10, no clear distinction could be made from the expression profiling of other B-cell lymphomas claimed to be derived from marginal zone B cells. Additionally, the immunophenotype of the tumoral cells in all cases but one differed from that described in monocytoid B cells. It was characterized by a Bcl2-, p21+, cyclin E+ profile. The analysis of apoptosis-regulator proteins disclosed abnormalities in the expression of survivin and active caspase 3, which could partially explain the abnormal regulation of apoptosis observed in these tumors. Molecular and immunohistochemical data obtained in this study strongly imply that there is significant heterogeneity among the cases included in the category termed nodal marginal zone lymphoma.

Clinicopathological features of gastric B-cell lymphoma: a series of 317 cases

The stomach is a common site of extranodal malignant lymphoma. Here we examined the clinicopathological features of 317 gastric B-cell lymphomas and characterized the differences among low-grade mucosa-associated lymphoid tissue (MALT) lymphomas (LG), high-grade MALT lymphomas (HG), follicular lymphomas (FL) and diffuse large B-cell lymphomas (DL). Cases included 126 DL, 71 HG, 98 LG, 10 FL, three Burkitt's lymphoma and nine of undefined type. The age range of patients was as follows: LG, 14-96 years (mean, 61.1); HG, 20-87 years (mean, 63.9); DL, 16-88 years (mean, 62.8); and FL, 54-76 years (mean, 65.5). There were no differences in age with respect to tumor type. There were more women patients with LG (female:male, 55:43), while males predominated among DL patients (54:72). The sexes were represented almost equally in HG cases (34:37). Histological findings, especially in DL tumors, correlated significantly to the gross appearance of mass formation. Dutcher bodies were encountered mainly in HG or LG cases. Our results showed no differences in age, sex or site of disease between LG, HG and DL tumors. However, the grade of malignancy correlated strongly to gross appearance. Dutcher bodies were important for the diagnosis of gastric MALT lymphoma.

Follicular hyperplasia presenting with a marginal zone pattern in a reactive lymph node lesion

Histologically, the marginal zone pattern of the lymph node is characterized by lymphoid follicles with three distinct layers. The inner layer is composed of follicular center zones, the middle layer of darkly stained mantle zones, and the outer layer of marginal zones. However, the marginal zone pattern is rarely seen in reactive lymph nodes except for mesenteric lymph nodes. We describe the clinicopathologic, immunohistochemical and genotypic findings of six cases of reactive follicular hyperplasia exhibiting the marginal zone pattern. The patients comprised three males and three females (age range 24 to 63 years; medium 56 years). Follow-up data were obtained from five patients. None of them developed malignant lymphomas during the follow-up period of from 5 to 204 months (median 68 months). Histologically, the lesion was characterized by numerous lymphoid follicles and partial distortion of lymph node structure. Varying degrees of progressive transformation of the germinal center (PTGC) were noted in the four cases. The marginal zone pattern was observed in some or most of the lymphoid follicles including PTGC. The marginal zone B cells were small to medium-sized lymphocytes with round or slightly indented nuclei and a broad rim of pale cytoplasm. Some of them had a monocytoid appearance. They were CD20+, CD79a+, sIgM+/-, sIgD-, CD5-, CD10-, CD21-, CD23-, CD43-, CD45RO-, Bcl-6-, cyclin D1-, EMA- and p53-. A portion of them were Bcl-2 positive. Occasional large lymphoid cells with round or indented nuclei and moderate amounts of cytoplasm were observed in the marginal zone in four cases. These large lymphoid cells were usually CD20 positive, but Bcl-6 negative. A small number of them contained polytypic intracytoplasmic immunoglobulins. The polytypic nature of B lymphocytes was demonstrated by immunohistochemistry and polymerase chain reaction. Recognition of unusual marginal zone hyperplasia in reactive lymph node lesions is important to avoid confusion with nodal involvement in various low-grade B cell lymphomas presenting a marginal zone distribution pattern.

Marginal zone cell lymphoma--an update on recent advances

The marginal zone represents one of the distinct compartments of the B-cell area in lymphoid tissues. It is especially well developed in the spleen and in Peyer's patches of the gut, but not in lymph nodes, with the exception of the ones in the mesenterium. However, the pronounced proliferation of so-called 'monocytoid B-cells' that may be seen in some inflammatory conditions of the lymph node may be regarded as a nodal reactive marginal zone cell expansion. The cellular compositions of the marginal zone and the monocytoid B-cell proliferation are similar and both show a heterogeneous population of B-cells, of which the functions are being slowly unravelled. Neoplasms originating in the marginal zone have been recognized in the past and are listed in the REAL classification as marginal zone B-cell lymphomas including extranodal MALT-type lymphomas, splenic marginal zone lymphomas and nodal (monocytoid) marginal zone lymphomas. Marginal zone cell lymphomas display a broad morphological spectrum, which is reflected by the heterogeneity of the cellular composition and the variation in the growth pattern of the lymphoma, but is independent of the anatomical site. All three marginal zone cell lymphomas share immunophenotypic, genetic and chromosomal similarities which will be discussed. The morphologic features are dealt with only briefly as they have been extensively discussed elsewhere.

Marginal-zone B-cell lymphoma of extranodal mucosa-associated lymphoid tissue type: molecular genetics provides new insights into pathogenesis

Marginal zone B-cell lymphoma of extranodal mucosa-associated lymphoid tissue (MALT) type is recognized as a distinct clinicopathologic entity in the revised European-American lymphoma (REAL) and recently published World Health Organization (WHO) classifications. These neoplasms are thought to arise from the extranodal equivalent of the lymph node marginal zone. Two recurrent chromosomal translocations, to date, have been implicated in the pathogenesis of these neoplasms. The t(11;18)(q21;q21), which is far more common, disrupts the api2 gene on chromosome 11q21 and the malt1 (mlt) gene on chromosome 18q21, resulting in the synthesis of a novel fusion gene and protein, API2-MALT1. The t(1;14)(p22;q32), which is uncommon, juxtaposes the bcl-10 gene on chromosome 1p22 adjacent to the immunoglobulin heavy chain (IgH) gene on chromosome 14, wherein BCL10 is overexpressed via the influence of the IgH enhancer. BCL-10 may then form a complex with MALT1 in the cell. Both translocations result in increased inhibition of apoptosis, conferring a survival advantage. Recent work suggests that API2-MALT1 and BCL-10-MALT1 may activate NF-kB and a common downstream signaling pathway.

Splenic marginal zone lymphoma with or without plasmacytic differentiation

We report a series of 31 cases of splenic marginal zone lymphomas with an enlarged spleen and a multimicronodular macroscopic pattern. Two groups, A and B, were distinguished based on the presence (A) or absence (B) of a lymphoplasmacytic component with monoclonal immunoglobulin expression in the cytoplasm. There were no differences between the groups as far as age, sex, spleen weight, and progression. The only difference was the presence in group A of a monoclonal serum component and autoimmune disorders, particularly autoimmune hemolytic anemia. In most cases in which a liver and/or bone marrow biopsy was performed, lymphomatous infiltration was detected. Seven cases had a seric monoclonal IgM of 5 g/L or more and liver or bone marrow infiltration, corresponding to the definition of Waldenstrom's macroglobulinemia. Lymphoma cells had a monocytoid, centrocytoid and, in group A, lymphoplasmacytic morphology. The lymphomatous cells were positive for CD20, CD45 RA, and bcl-2. They expressed IgD in 9 cases, partially in 6, and were negative for IgD in 9 of the 24 cases studied. Progression seems to be slow, with a long survival. Three patients presented with transformation into a large B-cell lymphoma, which was responsible for death in two patients.

The skin-associated lymphoid tissue-related B-cell lymphomas

Primary cutaneous B-cell lymphomas (CBCLs) should be clearly separated from non-Hodgkin's B-cell lymphomas with secondary cutaneous involvement and from cutaneous B-cell pseudolymphomas. The majority of CBCLs are characterized by a homogeneous clinical presentation and behavior, with good response to local radiotherapy, low tendency to extracutaneous spread, and excellent prognosis. According to the European Organization for Research on the Treatment of Cancer classification of primary cutaneous lymphomas, CBCLs with an indolent behavior are divided into 2 subgroups: follicular center cell lymphoma and immunocytoma/marginal zone lymphoma, due to putative histologic similarities with their purported nodal counterparts. In addition, a third subgroup with intermediate prognosis (large B-cell lymphoma of the leg) is identified. Conversely, the identification of distinct subgroups is disputable from a strictly histologic, immunophenotypic, and genotypic point of view, and has neither correlation with the clinical course nor the prognosis of the disease. Moreover, the majority of CBCLs show a uniform immunophenotype (CD5-, CD10-) and genotype (lack of bcl-1/bcl-2 and c-myc gene rearrangement) of neoplastic cells. Therefore, we favor the use of the term Skin-Associated Lymphoid Tissue (SALT)-related B-cell lymphomas, due to the close similarities between CBCLs and mucosa-associated lymphoid tissue (MALT) lymphomas, and the evidence for an acquired B-cell arm of SALT.

Incidence and subtype specificity of API2-MALT1 fusion translocations in extranodal, nodal, and splenic marginal zone lymphomas

The t(11;18)(q21;q21) is thought to represent an important primary event in the development of marginal zone lymphomas, although an accurate estimation of the frequency and distribution of this genetic alteration among nodal, splenic, and extranodal marginal zone lymphoma types has yet to be determined. Recently, molecular genetic studies have shown that this translocation results in the fusion of the API2 gene on chromosome 11 and a novel gene termed MALT1 on chromosome 18. To investigate the incidence of API2-MALT1 fusion transcripts among marginal zone lymphomas and to determine possible marginal zone lymphoma subtype associations, we used reverse transcriptase-polymerase chain reaction to analyze RNAs extracted from frozen tissue samples of 99 marginal zone lymphomas. Fifty-seven involved diverse extranodal sites including 14 stomach, 11 lung, 7 orbit, 7 parotid, 5 thyroid, 5 lacrimal gland, 3 small intestine, 2 large intestine, 1 kidney, 1 paraspinal region and 1 skin. Twenty-one primary splenic and twenty-one primary nodal marginal zone lymphomas were also studied. API2-MALT1 fusion transcripts were detected in 12 of 57 extranodal marginal zone lymphomas (21%), but in none of the nodal or splenic cases. The cDNA sequences of the fusion transcripts were determined, revealing variation in the coding sequence fusion point for both API2 and MALT1. The findings suggest that t(11;18)(q21;q21) is restricted to extranodal marginal zone lymphomas and that these tumors have distinct genetic etiologies in comparison with their splenic and nodal counterparts.

Clinicopathological features of gastric mucosa associated lymphoid tissue (MALT) lymphomas: high grade transformation and comparison with diffuse large B cell lymphomas without MALT lymphoma features

AIMS

To investigate the clinicopathological differences among gastric low grade MALT lymphomas (low MALT), large B cell lymphomas with low grade components (secondary high grade MALT lymphomas, high MALT), and diffuse large B cell lymphomas without low grade features (primary high grade MALT lymphomas, DLL).

METHODS

Clinicopathological and morphological characters of 126 gastric lymphoma cases were studied: 82 cases of low MALT lymphoma including 40 that were surgically resected, 17 cases of high MALT lymphoma including 13 surgically resected, and 27 cases of DLL including 12 surgically resected.

RESULTS

Age ranges were as follows: low MALT lymphoma, 34 to 85 years (mean 59.9); high MALT lymphoma, 53 to 88 years (mean 68.5); DLL, 29 to 83 years (mean 62.3). The average age for low and high MALT lymphomas was significantly different (p < 0.05), but there were no differences in other comparisons. There was a female predominance of low MALT lymphoma patients (female to male ratio, 47/35), while for high MALT patients the ratio was almost even (8/9), and for DLL patients there was a male predominance (11/16). Examination of surgically resected material showed that MALT lymphomas had a wider distribution in the gastric wall than DLL.

CONCLUSIONS

The findings suggest that at least some of the high grade gastric lymphomas, especially in patients younger than the fifth decade, do not originate from high grade transformation of low MALT lymphomas. It seems to take about one decade at least for high grade transformation of low MALT lymphomas.

Exclusive detection of the t(11;18)(q21;q21) in extranodal marginal zone B cell lymphomas (MZBL) of MALT type in contrast to other MZBL and extranodal large B cell lymphomas

Extranodal mucosa-associated lymphoid tissue (MALT)-type lymphomas and nodal and splenic marginal zone B cell lymphomas (MZBL) share morphological and immunophenotypic features with marginal zone B cells of reactive lymphoid tissues. Although displaying a similar immunophenotype, recent investigations suggest fundamental genetic differences among these subgroups. To determine the prevalence of the t(11;18) in a larger series of MALT-type lymphomas and to investigate a possible occurrence in other lymphomas, we screened 106 non-Hodgkin's lymphomas (NHL) by interphase cytogenetics using yeast artificial chromosome (YAC) probes flanking the breakpoint at 11q21. A signal constellation indicating a disruption in 11q21 and thus pointing to the presence of the t(11;18) was observed in 9 of 33 (27%) low-grade lymphomas of MALT type. The complete absence of t(11;18)-positive cells in 32 primary and secondary extranodal high-grade lymphomas suggests that low-grade lymphomas of MALT type characterized by the t(11;18) are unlikely to transform into high-grade tumors. The absence of tumor cells carrying the t(11;18) in nodal MZBL challenges the assumption that most, if not all, of these tumors represent the nodal manifestation of a so far undetected low-grade lymphoma of MALT type. The t(11;18) was not detected in a single case of 29 splenic MZBL investigated. This observation strengthens the view that splenic MZBL are biologically different from extranodal MZBL of MALT type.

Marginal zone B-cell lymphoma: A clinical comparison of nodal and mucosa-associated lymphoid tissue types. Non-Hodgkin's Lymphoma Classification Project

PURPOSE

In the International Lymphoma Study Group classification of lymphoma, extranodal marginal zone B-cell lymphoma (MZL) of mucosa-associated lymphoid tissue (MALT) type is listed as a distinctive entity. However, nodal MZL is listed as a provisional entity because of questions as to whether it is truly a disease or just an advanced stage of MALT-type MZL. To resolve the issue of whether primary nodal MZL without involvement of mucosal sites exists and whether it is clinically different from extranodal MALT-type lymphoma, we compared the clinical features of these two lymphomas.

PATIENTS AND METHODS

Five expert hematopathologists reached a consensus diagnosis of MZL in 93 patients. Seventy-three were classified as having MALT-type MZL because of involvement of a mucosal site at the time of diagnosis, and 20 were classified as having nodal MZL because of involvement of lymph nodes without involvement of a mucosal site.

RESULTS

A comparison of the clinical features of nodal MZL and MALT-type MZL showed that more patients with nodal MZL presented with advanced-stage disease (71% v 34%; P =. 02), peripheral lymphadenopathy (100% v 8%; P <.001), and para-aortic lymphadenopathy (56% v 14%; P <.001) than those with MALT-type MZL. However, fewer patients with nodal MZL had a large mass (> or = 5 cm) than those with MALT-type MZL (31% v 68%; P =.03). The 5-year overall survival of patients with nodal MZL was lower than that for patients with MALT-type MZL (56% v 81%; P =.09), with a similar result for failure-free survival (28% v 65%; P =.01). Comparisons of patients with International Prognostic Index scores of 0 to 3 showed that those with nodal MZL had lower 5-year overall survival (52% v 88%; P =.025) and failure-free survival (30% v 75%; P =.007) rates than those with MALT-type MZL.

CONCLUSION

Nodal MZL seems to be a distinctive disease entity rather than an advanced stage of MALT-type MZL because the clinical presentations and survival outcomes are different in these two types of MZL. Clinically, nodal MZL is similar to other low-grade, node-based B-cell lymphomas, such as follicular and small lymphocytic lymphomas.

Primary nodal marginal zone lymphomas of splenic and MALT type

The existence of primary nodal marginal zone lymphomas (MZL) is controversial, as is their relationship to putative extranodal counterparts. Most nodal lymphomas with monocytoid B cell/marginal zone differentiation exhibit the morphologic and immunophenotypical characteristics of extranodal MALT-lymphomas. Splenic marginal zone lymphoma (SMZL) is also of putative marginal zone derivation, but it differs immunophenotypically from MALT lymphoma. To clarify the relationship between nodal and extranodal MZLs and to investigate the possible existence of a nodal variant of SMZL, 36 MZL initially considered to be primary nodal neoplasms were examined. Other low-grade lymphomas with marginal zone differentiation were excluded (small lymphocytic lymphoma/chronic lymphocytic leukemia [SLL/CLL], follicular lymphoma, and mantle cell lymphoma). Six nodal MZLs showed morphologic and phenotypic characteristics similar to those of SMZL, whereas 30 tumors were more similar to MALT-type lymphomas. The six tumors with SMZL features showed a polymorphic infiltrate surrounding residual germinal centers with absent or very attenuated mantle cuffs. These lymphomas were IgD positive (6/6) but cyclin D1 (0/5), CD5 (0/6), and CD23 (0/6) negative. Five of these patients came for treatment in stage I or II. No patient manifested splenomegaly, peripheral blood, and/or bone marrow infiltration either at diagnosis or during follow-up. Lymph nodes from 30 patients with MALT-type features showed a perisinusoidal and perivascular infiltration of monocytoid/centrocytoid cells and residual germinal centers with a relatively well-preserved mantle cuff. The neoplastic cells were negative for IgD (0/17), cyclin D1 (0/8), and CD5 (0/12). Seven of 16 (44%) patients with a detailed history and clinical follow-up had evidence of extranodal lymphoma. These observations suggest that most nodal B cell lymphomas with marginal zone differentiation are of the MALT type and that they are frequently associated with an extranodal component. In addition, a primary nodal counterpart of splenic MZL also exists, and may occur in the absence of splenomegaly.

Fine-needle aspiration biopsy of large-cell undifferentiated carcinoma of the salivary glands: presentation of two cases, literature review, and differential cytodiagnosis of high-grade salivary gland malignancies

Primary undifferentiated carcinoma of the salivary glands is a rare, high-grade neoplasm which accounts for a very small number (1-5.5%) of malignant salivary gland tumors. The large-cell variant (LCU) is less well-characterized than the small-cell form. We report on the fine-needle aspiration (FNA) biopsy findings of 2 cases of LCU, one arising in the parotid gland, and the other in a buccal mucosa accessory salivary gland. The 2 cases were similar in composition: isolated and loosely cohesive large cells with abundant cytoplasm, and variability pleomorphic nuclei with prominent nucleoli. One case also featured multinucleated tumor giant cells and macrophage polykaryons; the latter has not previously been described in FNA biopsies of LCU. There was no evidence of squamous, myoepithelial, or widespread mucinous differentiation by morphological, cytochemical, or immunohistochemical analyses (focal rare mucin production identified on special stains in one case). The differential diagnosis is lengthy and consists of other high-grade primary salivary gland malignancies as well as metastatic lesions, including melanoma. The pattern of immunohistochemical reactivity (positive keratin, negative S-100, and HMB-45 antigens), and lack of conspicuous mucin production of significant lymphoidinfiltrate, were useful in establishing the correct diagnosis.

Gastric low-grade mucosa-associated lymphoid tissue lymphomas: their histogenesis and high-grade transformation

Gastric low-grade mucosa-associated lymphoid tissue (MALT) lymphoma is a unique disease. A vast majority of lymphoma cells are centrocyte-like cells or resemble monocytoid B cells, and occasionally show plasmacytic differentiation. Immunophenotypical and immunogenotypical examinations have indicated that they are in the differentiation stage of memory B cells, whose normal counterparts are marginal zone lymphocytes or monocytoid B cells in the lymphoid tissues. It arises from chronic gastritis closely associated with Helicobacter pylori (H. pylori) infection. Mucosa-associated lymphoid tissue lymphomas of other organs are also based on acquired MALT associated with chronic inflammation or autoimmune diseases. Interestingly, the majority of gastric low-grade MALT lymphomas regress by the eradication of H. pylori. The lymphoma cells, however, are not derived from B cells reacting with H. pylori itself but from autoreactive B cells. Although the mechanism of their oncogenesis has not been clarified, previous data suggest that autoreactive B cells proliferate in response to H. pylori-specific T cells, presumably with some cytokines. The genetic instability of such B cells then induces chromosomal abnormalities including trisomy 3 and/or other genetic changes. These B cells have the ability of autonomic proliferation and, even so, they might be sensitive to T cell stimuli. Low-grade gastric lymphomas occasionally progress to high-grade malignancy. The high-grade component of MALT lymphomas are composed of large-sized lymphoma cells that are morphologically indistinguishable from nodal large B cell lymphomas. This high-grade transformation is associated with p53 abnormalities or Bcl-6 overexpression. Gastric MALT lymphoma may provide a useful model in understanding multistep lymphomagenesis.

Marginal zone B-cell lymphomas including mucosa-associated lymphoid tissue type lymphoma (MALT), monocytoid B-cell lymphoma and splenic marginal zone cell lymphoma and their relation to the reactive marginal zone

The marginal zone of the B follicle represents a well-defined compartment of the B area. Its cellular composition is distinct from that of the follicle centre, from which it also differs in its functional role in the immune response. Several newly identified lymphoma entities, e.g. extranodal MALT type lymphoma, nodal monocytoid B-cell lymphoma and splenic marginal zone B-cell lymphoma, display in common a very peculiar organoid growth pattern reminiscent of the marginal zone. Moreover, their neoplastic components share morphologic and phenotypic similarities to the cellular components of the marginal zone. The clinical characteristics of these various marginal zone cell lymphomas may differ depending of the organ which is involved. Nevertheless, they all share common cytogenetic abnormalities suggesting a common pathogenesis.

Massive crystal-storing histiocytosis associated with low-grade malignant B-cell lymphoma of MALT-type of the parotid gland

Massive crystal deposition is unusual in lymphoproliferative disorders. In this report, a mucosa-associated lymphoid tissue (MALT) low-grade B-cell lymphoma of the parotid gland containing large numbers of crystal-storing histiocytes is described. The patient, an 81-yr-old female, presented with a history of long-standing left parotid gland enlargement. FNA cytology of the tumor showed a lymphoplasmacytic infiltrate and sheets of large benign histiocytes with abundant eosinophilic intracytoplasmic inclusions. Paraffinsection immunohistochemistry performed on the cell block demonstrated that the histiocytic cells were immunoreactive for the KP-1 (CD-68) antibody and monotypic for cytoplasmic IGM and L-light chain. The cytological diagnosis was consistent with a low-grade B-cell lymphoma with plasmacytic differentiation associated with crystal-storing histiosis. A periparotid lymph node was biopsied and showed involvement by a monocytoid B-cell lymphoma with plasmacytic differentiation and crystal-storing histiocytosis in the pericapsular region.

Marginal zone B-cell lymphomas: an appraisal

Although the Revised European-American Lymphoma Classification does not utilize the term monocytoid B-cell Lymphoma, there are numerous reasons to support its use in classifying lymphomas of so-called marginal zone B-cell type that contain a distinct population of malignant monocytoid B-cells. In addition, there are other B-cell lymphomas which have very distinctive morphological features, because they show multiple and very well demarcated histologies characterized by presence of cells that appear to be (1) malignant monocytoid B-cells and malignant follicular center cells, or (2) malignant monocytoid B-cells, malignant follicular center cells and malignant plasma cells, or (3) malignant monocytoid B-cells and malignant mantle cells. The neoplastic cells in each of the above three examples show identical light chain restriction and thus they are part of the same neoplastic clone. We believe that there are different types of precursor B-cells (memory or otherwise) for the above cells, and an arrest in differentiation of these precursor B-cells may readily explain the presence of these different morphological combinations. Recognition of these morphological types may lead to further awareness of the possibilities of the existence of multiple, linked pathways of differentiation for lymphoid cells including the possibility of different types of precursor B-cells. Furthermore, an understanding of the uniqueness of monocytoid B-cells would allow pathologists to use terminology that is less redundant and more precise.

Lymphoma in Sjögren's syndrome. From histopathology to molecular pathology

A number of autoimmune diseases predispose to the development of neoplasia. A particularly well-recognized association is the development of lymphoma in Sjögren's syndrome. Although this risk has been estimated to be 44 times that of the general population, few reliable prognostic indexes exist for individual patients. Recent advances in molecular biology have improved our understanding of Sjögren's syndrome and permitted better characterization of the generalized lymphoproliferation associated with the condition. This article reviews the histopathology of the major and minor salivary gland lesions of Sjögren's syndrome and discusses advances in molecular biology that have permitted more accurate prediction of lymphoma development in this group of patients.

Gastric malt lymphoma with crystalline immunoglobulin inclusions and secondary immunoblastic lymphoma in a cervical lymph node

A case of gastric B cell lymphoma of the mucosa-associated lymphoid tissue (MALT) with crystalline immunoglobulin inclusions in monotypic plasma cells is reported, which initially presented as a secondary immunoblastic lymphoma in a cervical lymph node. The low-grade MALT lymphoma was diagnosed 14 months after detection of the nodal high-grade lymphoma, but rare crystal-containing plasma cells of identical immunoglobulin isotype found in the immunoblastic lymphoma retrospectively confirmed a common clonal origin. The diagnostic significance of crystalline immunoglobulin inclusions and the unusual initial presentation of MALT lymphoma as a secondary high-grade lymphoma at a distant nodal site are discussed.

Immunosuppression-associated lymphoproliferative disorders in rheumatic patients

The association between rheumatic disease and the occurrence of hematolymphoid neoplasms has been a subject of investigation for many years. Recently, we and others have reported the development in rheumatic patients of lymphoproliferative disorders that are similar to those occurring in patients with known immunocompromised states. The lymphoid neoplasms that develop in patients with immunosuppression are characterized by several features including the presence of EBV genome in the neoplastic cells. The fact that lymphomas with features of those occurring in immunosuppressed patients can occur in patients with rheumatic disease suggests that immune system impairment secondary to the rheumatic disease, the treatment given for the rheumatic disease, or to a combination of these factors, might play a role in the development of lymphoma in these patients. This review will first describe the characteristics of lymphoproliferative disorders that occur in patients with known immunocompromised states. It will then review general aspects of lymphomas in rheumatic patients with a focus on more recent reports that have described the development of immunosuppression-associated lymphoproliferative disorders in rheumatic patients. Studies that investigate the relative contribution of the rheumatic disease versus therapy for rheumatic disease in the development of lymphoma in this patient group are still needed.

Primary Sjögren's syndrome (SS) and malignant lymphoma. A retrospective cohort study of 55 patients with SS

The aim of this study was to assess the prevalence of malignant lymphomas in patients with long-standing primary Sjögren's syndrome (pSS). We retrospectively studied a cohort of 55 patients with pSS over a mean follow-up period of 12 years. Five patients (9%) developed malignant lymphoma. The interval between the diagnoses of SS and lymphoma ranged from four to 12 years (mean = 6.5 years). The lymphoma arose in the lymph nodes in two cases, the parotid gland in one case, the lacrimal gland in one case, and the lung in one case. All five cases were B-cell low-grade lymphomas. Among our SS patients, those with extraglandular manifestations and/or a mixed cryoglobulin were at increased risk for lymphoma development. Secondary lymphoma carried a poor prognosis in our study. Three of the six SS patients who died during the follow-up period had lymphoma.

bcl-1, bcl-2, p53, c-myc, and lyt-10 analysis in cutaneous lymphomas

In the present study we investigated the pathogenetic role of c-myc, bcl-2, and lyt-10 oncogenes, bcl-1 locus, and p53 suppressor gene in a representative panel of cutaneous lymphomas, including 25 cases of cutaneous B cell lymphoma (CBCL) and 29 cases of cutaneous T cell lymphoma (CTCL). In our analysis four cases of CBCL were found rearranged for bcl-2 and two for the bcl-1 locus. Two cases of CTCL and one case of CBCL were found rearranged for lyt-10. No rearrangements of c-myc oncogene were found in CBCL. Analysis of p53 gene showed mutation only in one case of mycosis fungoides in tumoral stage, at codon 163 of p53 gene (TAC-->CAC; Tyr--> Asp). Our data suggest that in primary CBCL bcl-2 oncogenes and bcl-1 locus are rarely involved. Furthermore, in primary CTCL p53 gene is not affected at significant frequency. The occurrence of p53 mutation in a patient affected by mycosis fungoides in tumoral stage may represent an involvement of p53 gene in tumor progression of CTCL, a finding observed in several types of human cancer.

UCL3D3 and UCL4D12 reactivity in small B-cell neoplasms with special emphasis on monocytoid B-cell lymphoma

Two recently described monoclonal antibodies, UCL3D3 and UCL4D12, have been reported to have some specificity for mantle zone B lymphocytes and marginal zone/follicular center B lymphocytes, respectively, in the spleen. Forty-nine B-cell neoplasms, including 20 cases of monocytoid B-cell lymphoma (MBCL), were studied by frozen section immunohistochemistry with these antibodies to evaluate their utility. Tonsil, lymph node, and reactive spleen also were studied with the antibodies. Although a wide overlap was observed among the different lymphomas, a majority of cases of MBCL and half of cases of hairy cell leukemia (HCL) reacted with both markers, suggesting both marginal/follicular and mantle cell antigen expression. None of four cases of mantle cell lymphoma reacted with the proposed mantle cell marker UCL3D3, whereas three of these cases immunoreacted with UCL4D12. This marker is known to react with a subpopulation of follicular center cells and possibly with marginal zone lymphocytes. A comparison of nodal and extranodal neoplasms failed to show a significant difference in the pattern of immunoreactivity with these antibodies. Tonsil and lymph node controls showed some mantle zone staining with both antibodies, and there was a slight overlap in mantle and marginal zone staining of the spleen controls. These findings suggest an immunologic similarity between some cases of HCL and MBCL. However, the findings also would suggest that these antibodies, particularly UCL4D12, have less specificity than has been previously assumed, and UCL4D12 may not have practical utility in the evaluation of low grade B-cell lymphomas.

Primary breast lymphoma with skin involvement arising in lymphocytic lobulitis

Primary breast lymphoma is a rare tumour which has recently been associated with pre-existing lymphocytic lobulitis. We report a patient with lymphocytic lobulitis in whom the lymphoma recurred in the contra-lateral breast 5 years after the initial presentation, to be followed shortly afterwards by skin involvement. This progression illustrates the relationship between extra-nodal lymphomas and underlying autoimmune disease and the homing of lymphomas to related sites.

The cytological spectrum of the monocytoid B-cell reaction: recognition of its large cell type

To analyse the cytological features of benign monocytoid B-cells, we investigated, histologically and immunohistochemically, 78 reactive lymphadenopathies expressing monocytoid B-cell reactions. Within a broad cytological spectrum of reactive monocytoid B-cells, two cytological types can be recognized: 1 the common type composed of medium-sized cells with irregular or bean-shaped nuclei and inconspicuous nucleoli, and 2 the large cell type composed of cells considered to represent large transformed monocytoid B-cells, with less pleomorphic round nuclei with vesicular chromatin and moderately basophilic, prominent nucleoli. In between these variants transitional forms showing evolution to large transformed monocytoid B-cells occurred. While monocytoid B-cell reactions in 70.5% of all cases were composed predominantly of the common type of monocytoid B-cells, in 29.5% of cases the large transformed cells prevailed. The two distinctive cytological types of reactive monocytoid B-cells seem to have their neoplastic counterparts in monocytoid B-cell lymphoma, including its large cell variant.