Characteristics and natural course of hypoechoic thyroid lesions diagnosed as possible thyroid lymphomas by fine needle aspiration cytology

Background

There is little information regarding the natural course of hypoechoic thyroid lesions that are probable or possible thyroid lymphoma based on fine needle aspiration cytology (FNAC) results.

Methods

Sixty-five patients who were diagnosed as probable or possible thyroid lymphoma by ultrasonography (US) and FNAC were investigated. Forty-three patients with strong suspicion underwent thyroid surgery for the diagnosis at our hospital, and 22 patients were followed up with periodic US examination. Thyroid lymphoma was definitely diagnosed in 41 out of 43 patients who underwent thyroid surgery, and such patients were defined as Group A. The outcomes of 22 patients who were followed up without an immediate therapy were analyzed. Their hypoechoic lesions decreased in size (n = 10) or disappeared (n = 2) in 12 of 22 patients, and such patients were defined as Group B. Patients in Group A and B were compared using the Kuma Hospital-US classification (USC), the diagnostic categories of the Bethesda System for Reporting Thyroid Cytopathology, and the κ/λ deviation of the immunoglobulin light chain in the FNAC specimens. Mann-Whitney U-test and chi-squared test (with Yate’s continuity correction) were used to compare the two groups.

Results

The USC of < 3.5 [9/12 (75.0%) in Group B; 10/41 patients (24.4%) in Group A] and the κ/λ deviation ratio of < 3.40 [11/12 (91.7%) in Group B; 17/41 patients (41.5%) in Group A] were significantly more frequent (p < 0.01), and the FNAC of ‘benign’ or ‘atypia of undetermined significance or follicular lesion of undetermined significance (AUS)’ with a comment of possible lymphoma [9/12 (75.0%) in Group B; 12/41 patients (29.3%) in Group A] was significantly more frequent (p < 0.05) in Group B than Group A.

Conclusions

Our study suggests that some hypoechoic thyroid lesions that are possible thyroid lymphoma based on US and FNAC might decrease in size or disappear during the careful observation.

Review article: common misconceptions in the management of Helicobacter pylori-associated gastric MALT-lymphoma

BACKGROUND

Helicobacter pylori infection is the main cause of gastric mucosa-associated lymphoid tissue (MALT) lymphoma.

AIM

To review several common misconceptions in the management of H. pylori-associated gastric MALT-lymphoma.

METHODS

Bibliographical searches were performed in MEDLINE up to June 2011.

RESULTS

If adequate diagnostic methods are used, and if only low-grade lymphomas are considered, the prevalence of H. pylori infection is very high (almost 90%). H. pylori eradication is effective in treating approximately 80% of patients with early stage lymphoma. In H. pylori-positive gastric high-grade lymphomas, antibiotic therapy should always be prescribed, as approximately 50% of them regress after H. pylori eradication. Patients with early stage MALT lymphoma negative for H. pylori might still benefit from antibiotic treatment as the sole treatment. Complete remission of gastric MALT lymphoma after H. pylori eradication can take even >12 months. PCR assay for the detection of monoclonal B cells remains positive in many cases after complete remission has been reached. Patients with a persistent clonal band should not be treated unless the lymphoma can be histologically demonstrated. Synchronous occurrence of gastric adenocarcinoma and MALT lymphoma has been repeatedly reported. In some patients in complete remission, eradication of H. pylori does not prevent later development of early gastric cancer. Gastric lymphoma recurrence occurs in some patients after both bacterial and lymphoma regression. H. pylori reinfection does not constitute a prerequisite for lymphoma recurrence.

CONCLUSIONS

The present article states several misconceptions in the management of H. pylori-associated gastric MALT-lymphoma in clinical practice, reviews the related scientific evidence and proposes the adequate attitude in each case.

Treatment of extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue with fludarabine: effect on tumor microenvironment

Gastric Helicobacter pylori (HP) positive extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) develops during chronic antigenic stimulation with specific T-cell help. Chemotherapy that acts both on the malignant B-cells and on T-cells in the microenvironment, i.e. nucleoside analogs, might therefore be an attractive treatment. In 14 patients with gastric MALT lymphoma treated with fludarabine, alterations in T-cell subsets were studied in subsequent peripheral blood samples and in gastric biopsies. Treatment with fludarabine resulted in a steep decrease in T-cell subsets in peripheral blood samples. By contrast no decrease in T-cell populations was observed in subsequent gastric biopsy samples and a moderate increase was observed in relative infiltration with CD3 +, CD4 + and CD8 + cells. In addition an increase in density of FOXP3 + cells (i.e. Tregs) was seen (p = 0.047). These alterations in different T-cell subsets were not observed in gastric biopsy samples of patients treated with HP-eradication only.

Therapy of gastric mucosa-associated lymphoid tissue lymphoma

Mucosa-associated lymphoid tissue (MALT) lymphoma is a relatively common lymphoma and comprises approximately 7% of all newly diagnosed non-Hodgkin's lymphoma. It is mainly located in the stomach and has become a focus of interest due to its unique pathophysiological link with Helicobacter pylori (HP) and the consecutive response to HP eradication therapy. In view of this, HP eradication has become standard treatment for patients with localised disease, and recent data have suggested that HP-negative patients might benefit from antibiotic treatment. In case of non-response, however, the standard approach in such patients is unclear. Both radiation and chemotherapy have shown promising results, and at present there is only one randomised study, which nevertheless suggests chemotherapy as management of choice. The objective of this review is, therefore, to summarise and evaluate the data available for treatment of gastric MALT lymphoma and to highlight potential focus for further research.

Gastrointestinal lymphoma: where morphology meets molecular biology

Primary gastrointestinal lymphomas are best exemplified by mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach and enteropathy-type T-cell lymphoma (ETL). Both lymphomas were initially recognized on morphological grounds and their identification as distinct clinicopathological entities has subsequently been vindicated following integrated immunophenotypic, molecular, and cellular biological investigations. Delineation of the phenotypic, molecular, and biological properties of these lymphomas at various clinicopathological stages of their development has also provided critical information for the clinical management of patients with these diseases. Here, the histopathology and recent advances in phenotypic and molecular characterization of gastric MALT lymphoma and ETL and their applications in diagnosis and clinical management are reviewed.

Molecular biology methods for the characterization of Helicobacter pylori infections and their diagnosis

Helicobacter pylori infects approximately half of the human population; however, the outcome of infection is affected by many factors, including strain and host genotype characteristics and bacterial density within the stomach. Many molecular methods have been developed to provide information with respect to these characteristics. Methods that provide results within 24 h of endoscopy may be used to develop individualized treatment that is more effective, results in fewer side effects, cuts costs,decreases the number of treatment failures and results in the development of fewer antibiotic-resistant H. pylori strains.

The diminishing role of surgery in the treatment of gastric lymphoma

OBJECTIVE

This article reviews the pathogenesis, diagnosis, and treatment of patients with primary gastric lymphoma, with special attention to the changing role of surgery.

SUMMARY BACKGROUND DATA

Primary gastric lymphomas are non-Hodgkin lymphomas that originate in the stomach and are divided into low-grade (or indolent) and high-grade (or aggressive) types. Low-grade lesions nearly always arise from mucosa-associated lymphoid tissue (MALT) secondary to chronic Helicobacter pylori (H. pylori) infection and disseminate slowly. High-grade lesions may arise from a low grade-MALT component or arise de novo and can spread to lymph nodes, adjacent organs and tissues, or distant sites.

METHODS

A review of the relevant English-language articles was performed on the basis of a MEDLINE search from January 1984 to August 2003.

RESULTS

About 40% of gastric lymphomas are low-grade, and nearly all these low-grade lesions are classified as MALT lymphomas. For low-grade MALT lymphomas confined to the gastric wall and without certain negative prognostic factors, H. pylori eradication is highly successful in causing lymphoma regression. More advanced low-grade lymphomas or those that do not regress with antibiotic therapy can be treated with combinations of H. pylori eradication, radiation therapy, and chemotherapy. Nearly 60% of gastric lymphomas are high-grade lesions with or without a low-grade MALT component. These lymphomas can be treated with chemotherapy and radiation therapy according to the extent of disease. Surgery for gastric lymphoma is now often reserved for patients with localized, residual disease after nonsurgical therapy or for rare patients with complications.

CONCLUSION

The treatment of gastric lymphoma continues to evolve, and surgical resection is now uncommonly a part of the initial management strategy.

Monoclonality in Helicobacter pylori-positive gastric biopsies: an early detection of mucosa-associated lymphoid tissue lymphoma

Mucosa-associated lymphoid tissue (MALT) is not present in healthy gastric mucosa, but it can develop in sites of long-persisting inflammation and is connected with the development of MALT lymphoma. A monoclonal lymphocyte population is one of the characteristics of such lymphomas. In this study we analyzed gastric biopsies (formalin fixed and paraffin embedded or frozen) in 93 patients with dyspepsia accompanied by Helicobacter pylori infection. We applied PCR and single-cell immunocytochemistry to detect the clonality of the gastric B-cell population. Immunocytochemistry performed on 33 frozen biopsies showed two samples with monoclonal pattern. PCR analysis of immunoglobulin heavy-chain (IgH) gene rearrangements revealed two monoclonal populations out of 161 biopsies from 60 patients. We conclude that PCR analysis was the most sensitive method, which gave us insight into the nature of the earliest stage of MALT lymphoma in gastric biopsies.

Outcome in relation to treatment modalities in 48 patients with localized gastric MALT lymphoma: a retrospective study of patients treated during 1976-2001

The aim of this study was to retrospectively analyze survival and tumor response data in patients with localized gastric MALT lymphoma treated by different treatment modalities other than anti-Helicobacter pylori treatment (diagnosis made before 1993, or after failure of antibiotics + anti-acid), including surgery, chemotherapy or combined treatment. Here we studied a series of 48 patients with stage IE or IIE disease treated during the past 11 years. These patients received different treatments: chemotherapy was proposed to 19 (40%) patients; gastric surgery to 21 (43%) patients, consisting of partial gastrectomy of 7 patients and total gastrectomy in 14 patients; combined treatment to 8 (17%) patients, consisting of surgery + chemotherapy in 7 patients and surgery + chemotherapy + radiotherapy in 1 patient. At diagnosis, 85% of the patients had good PS and no B symptoms. Complete response after treatment was reached in 45 (94%) patients (chemotherapy: 84% of the patients; surgery alone: 95%; combined treatment: 100%). Progression was observed in 16 (33%) patients. No statistical difference in the survival was found among the different therapeutic modalities: 5-year overall survival year FFP survival was 81% for chemotherapy, 86% for surgery alone and 95% for combined treatment. Prognostic factors for survival were age, performance status and hemoglobin level at diagnosis. Considering the natural bias of a retrospective analysis, surgery or chemotherapy was associated with a similar outcome in patients with MALT lymphoma after antibiotics failure.

Treatment of extranodal lymphomas

At least one-quarter of the non-Hodgkin's lymphomas arise primarily at extranodal sites. The rising incidence of non-Hodgkin's lymphomas, observed over recent decades, have mainly affected the primary extranodal entities. Survival rates vary among the specific sites of primary extranodal lymphomas. This is due partly to differences in natural history, related mainly to the histological type but also to differences in management strategy which are related to organ-specific problems. Few controlled studies facilitate therapeutic decisions in this setting. This chapter represents a general overview of the available data.

Regression of CD5-positive and Helicobacter pylori-negative mucosa-associated lymphoid tissue lymphoma of the rectum after administration of antibiotics: report of a case

We report a case of mucosa-associated lymphoid tissue lymphoma of the rectum that regressed after antibiotics administration. A 70-year-old female complained of abdominal discomfort. Colonoscopy performed in July 1998 showed a hemispheric protrusion of the rectum, the surface of which was covered with normal rectal mucosa. Pathologic diagnosis of a biopsy specimen was low-grade mucosa-associated lymphoid tissue lymphoma. Gastroscopy showed multiple erosions of the antrum, and was negative by both culture and histology. After informed consent the patient was treated with a 14-day course of lansoprazole, amoxicillin, and clarithromycin for the eradication of. Repeat colonoscopy ten days after initiation of treatment showed that the rectal tumor had disappeared, and this was confirmed by histologic examination. There was no recurrence during 20 months of follow-up.

IgH PCR of zinc formalin-fixed, paraffin-embedded non-lymphomatous gastric samples produces artifactual "clonal" bands not observed in paired tissues unexposed to zinc formalin

Helicobacter pylori (HP) causes dense gastritis that can be difficult to distinguish morphologically from MALT-type lymphoma (ML). Immunoglobulin heavy chain (IgH) gene analysis by polymerase chain reaction (PCR) is often used to resolve diagnosis. However, monoclonal bands have been reported in nonmalignant cases of gastritis. Retrospectively, 16 gastric ML with both formalin-fixed, paraffin-embedded (FF-PE) and ethanol-fixed samples (EF), and 9 cases of FF-PE HP-gastritis were analyzed by IgH PCR to document the presence of non-reproducible bands in HP-gastritis, but not ML samples. In duplicate analyses, 12 of 16 ML yielded identical monoclonal bands in FF-PE and EF samples whereas 3 of 9 FF-PE gastritis cases yielded different-sized (ie, non-reproducible) "clonal" bands. Sequencing of two PCR products from a gastritis case confirmed IgH gene sequences. To investigate whether FF-PE had a direct effect on producing these non-reproducible bands, 7 gastrectomy samples were prospectively divided into EF and FF-PE halves for IgH PCR. All 7 samples demonstrated polyclonal smears in EF portions while 4 of 7 FF-PE portions yielded either multiple distinct bands or non-reproducible bands. In conclusion, IgH PCR of FF-PE tissue can create artifactual "clonal" bands, which are the appropriate product size, contain IgH sequences, and, if not performed in duplicate, may confuse interpretation of B-cell clonality.

Molecular phenotype distinguishes two subsets of gastric low-grade mucosa-associated lymphoid tissue lymphomas

Isotype switch recombination together with somatic mutation of immunoglobulin variable genes is indicative of B-cell maturation stage. Because aberrant isotype switch events occur in a proportion of gastric mucosa-associated lymphoid tissue (MALT) lymphomas, we tested whether gastric MALT lymphomas with or without aberrant rearrangements in the switch regions differ in B-cell maturation stage. Southern blot analysis of DNA from six gastric MALT lymphoma cases revealed the presence of aberrant isotype switch events in three cases. Somatic common mutations were present in all immunoglobulin variable heavy chain genes of the six cases, and homology with the closest germline ranged from 89.5% to 98.8%. Replacement versus silent mutation ratio analysis of complementarity-determining regions and frameworks indicated the positive selective pressure of an antigen in four cases. In the remaining two cases, protein translated from the third complementarity-determining region suggested the selective pressure of an autoantigen. The three cases with aberrant isotype switch events showed no uncommon mutations, whereas two of three cases without evidence of aberrant isotype switch showed high levels of such mutations. Moreover the three cases with aberrant isotype switch, compared with the three cases without, showed an increased number of common mutations and of N segment additions. These data raise the possibility of two distinct subsets of gastric low-grade MALT lymphomas, one with aberrant isotype switch and no intraclonal diversification, and one with no aberrant isotype switch but with intraclonal diversification. The first subset may originate from a post-germinal center environment and the second from a germinal center. Alternatively, the first subset may derive from the second after maturation or after a transformation event that blocks the mutational process.

Conservative treatment of primary gastric low-grade B-cell lymphoma of mucosa-associated lymphoid tissue: predictive factors of response and outcome

OBJECTIVES

Primary gastric low-grade B-cell lymphoma of mucosa-associated lymphoid tissue may regress with conservative treatment such as anti-Helicobacterpylori therapy or monochemotherapy. The aims of the present study were to analyze the predictive factors of response to anti-H. pylori treatment, to assess the effects of an adjuvant therapy in responding patients, and to evaluate an alternative therapy in nonresponding patients.

METHODS

From 1995 to 2000, 48 H. pylori-infected patients with localized primary gastric low-grade B-cell lymphoma of mucosa-associated lymphoid tissue were treated with anti-H. pylori therapy. Endoscopic and endoscopic ultrasonography features and histological grading of large cells' proportion were analyzed. Eradication of H. pylori and tumoral response were assessed at 2 and 6 months, respectively. From 1996, patients in remission at 6 months were randomized to receive either chlorambucil p.o. for 6 months or no treatment. Patients who did not respond to H. pylori eradication received chlorambucil p.o. for 1 yr.

RESULTS

Among the 48 treated patients, 33 (69%) were in complete (n = 28) or in partial (n = 5) remission, and 15 (31%) were in treatment failure at 6 months. H. pylori was eradicated in 47 patients. The response was not correlated with the endoscopic features or with the histological grade. In contrast, it was related to ultrasonographic features: remission was achieved in 76% of patients when no perigastric lymph node was detected versus only 33% when endoscopic ultrasonography showed presence of lymph nodes (p = 0.025). All responding patients remained in remission (median 34 months) whatever the treatment they received (no treatment or chlorambucil). Remission could be achieved with chlorambucil in 58% of the nonresponding patients to anti-H. pylori treatment.

CONCLUSIONS

The major negative predictive factor of the tumoral response to anti-H. pylori treatment in patients with primary gastric low-grade B-cell lymphoma of mucosaassociated lymphoid tissue was the presence of perigastric lymph nodes on endoscopic ultrasonography. In responding patients, remission remained stable, suggesting that adjuvant chemotherapy was not useful. In patients who failed to respond to H. pylori eradication, monochemotherapy with chlorambucil proved to be efficient, but new therapeutic modalities should be evaluated to improve the control of the tumoral process.

MALT lymphoma presenting as a cystic salivary gland mass

BACKGROUND

Mucosa associated lymphoid tissue (MALT) lymphoma has been noted to involve the salivary glands in chronic inflammatory conditions such as Sjogren's syndrome and in HIV infection.

METHODS AND RESULTS

The authors encountered a patient with bilateral cystic changes in the parotid glands which proved to be due to MALT lymphoma. The clinical course, histopathology, and treatment options of MALT lymphoma in the salivary gland are discussed in detail.

CONCLUSION

This malignant entity should be considered in the differential diagnosis of refractory cystic lesions of the salivary glands.

Helicobacter pylori eradication and remission of low-grade gastric mucosa-associated lymphoid tissue lymphoma: a long-term follow-up study

Helicobacter pylori infection plays a crucial role not only in the pathogenesis but also in the treatment of low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma. The aim of the present study was to evaluate whether H. pylori eradication provides a definite cure in the early stage of this neoplasia by means of a prolonged follow-up. All patients affected by low-grade gastric MALT lymphoma in stage IE that were referred to our department from January 1995 to June 1999 were enrolled in a prospective study. Diagnosis was histologically proved and H. pylori status was evaluated. Staging was performed according to a modified Ann Arbor classification. All patients who proved positive for H. pylori infection were treated with eradicating therapy, and a prolonged clinical and histologic follow-up was carried out. Until June 1999, seven low-grade gastric MALT lymphomas in stage IE were diagnosed (four men and three women; mean age, 56 years). All patients were H. pylori-positive and eradication was obtained in all of them after the first cycle of antibiotic therapy. Complete histologic regression of lymphoma was observed in all cases in a period variable between 3 and 6 months. The mean follow-up period was 42 months (range, 20-54). Only one patient showed a recurrence of lymphoma 22 months after treatment associated with H. pylori reinfection. Our results show the high efficacy of H. pylori eradication in determining a prolonged remission of low-grade gastric MALT lymphomas in stage IE. Thus, this therapeutic approach may avoid or delay the indication for more aggressive therapies, such as surgical resection.

Eradication of Helicobacter pylori and stability of remissions in low-grade gastric B-cell lymphomas of the mucosa-associated lymphoid tissue: results of an ongoing multicenter trial

The normal human stomach is devoid of any organized lymphatic tissue. Acquisition of mucosa-associated lymphatoid tissue (MALT) in the stomach is considered to be a direct consequence of chronic infection with Helicobacter pylori. Thus, MALT appears to be part of the host defense against the pathogen H. pylori. Consequently, lymphomas arising from gastric MALT may be seen as an end point of a clonal evolution starting from the infection. Cumulative data from several studies show that eradication of H. pylori induces complete histologic remissions in about 70%-80% of the patients. Here we present data of an extended analysis of an ongoing multicenter trial. Eighty-four patients with low-grade gastric MALT lymphoma in stage EI were treated using a dual regimen to eradicate H. pylori. Complete remission was observed in 68 (81%) patients; a partial remission was found in seven (8%) patients. In contrast, nine (11%) patients revealed "no change" and were referred for alternative treatment strategies. The majority of these cases were found to harbor high-grade lymphomas in deeper mucosal areas. Polymerase chain reaction (PCR) performed on the VDJ rearrangements of the immunoglobulin heavy chain yielded monoclonal bands in 50 of 65 analyzed patients (77%) at diagnosis. Interestingly, in patients analyzed during follow up after achieving complete histologic remission, ongoing PCR monoclonality was found in 19 of 39 eligible patients (49%). Several patients who developed local relapse of the lymphoma were found in the group with ongoing PCR monoclonality. Together with data from the literature, these results suggest that the majority of low-grade gastric MALT lymphomas in stage EI respond to eradication of H. pylori. Longer follow-up investigations are necessary to determine whether remissions really indicate a cure from the disease and to elucidate whether PCR monoclonality after complete histological remission is predictive of increased relapse rate.

Helicobacter pylori. One bacterium and a broad spectrum of human disease! An overview

Since the historical rediscovery of gastric spiral Helicobacter pylori in the gastric mucosa of patients with chronic gastritis by Warren and Marshall in 1983, peptic ulcer disease has been largely viewed as being of infectious aetiology. Indeed, there is a strong association between the presence of H. pylori and chronic active gastritis in histology. The bacterium can be isolated in not less than 70% of gastric and in over 90% of duodenal ulcer patients. Eradication of the organism has been associated with histologic improvement of gastritis, lower relapse rate and less risk of bleeding from duodenal ulcer. The bacterium possesses several virulence factors enabling it to survive the strong acid milieu inside the stomach and possibly damaging host tissues. The sequence of events by which the bacterium might cause gastric or duodenal ulcer is still not fully elucidated and Koch's postulates have never been fulfilled. In the majority of individuals, H. pylori infection is largely or entirely asymptomatic and there is no convincing data to suggest an increase in the prevalence of peptic ulcer disease among these subjects. An increasingly growing body of literature suggests an association between colonization by H. pylori in the stomach and a risk for developing gastric mucosa-associated lymphoid tissue (MALT), MALT lymphoma, gastric adenocarcinoma and even pancreatic adenocarcinoma. The bacterium has been implicated also in a number of extra-gastrointestinal disorders such as ischaemic heart disease, ischaemic cerebrovascular disease, atherosclerosis, and skin diseases such as rosacea, but a causal role for the bacterium is missing. Eradication of H. pylori thus seems to be a beneficial impact on human health. Various drug regimens are in use to eradicate H. pylori involving the administration of three or four drugs including bismuth compounds, metronidazole, clarithromycin, tetracyclines, amoxycillin, ranitidine, omeprazole for 1-2 weeks. The financial burden, side effects and emergence of drug resistant strains due to an increase in the use in antibiotics for H. pylori eradication therapy need further reconsideration.

Mucosa-associated lymphoid tissue-type lymphomas occurring in post-transplantation patients

Post-transplantation lymphoproliferative disorders (PTLDs) are usually Epstein-Barr virus (EBV)-associated B-cell lymphoproliferative disorders that vary in their morphologic spectrum. Extranodal marginal zone lymphomas of the mucosa-associated lymphoid tissue-type (MALT-type) have not been considered to be part of this spectrum. The authors encountered five such cases recently. The clinical, histopathologic, and immunophenotypic features are reported. There were three men and two women with a mean age of 51.2 years (range, 48-63 years). Two patients were cardiac transplant recipients, two patients were liver transplant recipients, and the remaining patient was a renal transplant patient. Sites of lymphoma were the stomach in three patients and the parotid gland in two patients. Mean time to the lymphoma was 84 months after transplantation. All patients had morphologic features of low-grade extranodal marginal zone lymphomas of the MALT-type, and Helicobacter pylori was present in all three gastric cases. All patients exhibited the B-cell immunophenotype and were negative for EBV by in situ hybridization. These lymphomas were treated with a variety of modalities, including reduction of immunosuppression, antibiotics, surgical resection, radiation therapy, and chemotherapy. At last follow-up, one patient had developed signet ring adenocarcinoma at 27 months but had no evidence of PTLD, one patient relapsed at 17 months but is alive with stable disease at 24 months, and the remaining patients were alive without disease at 11, 12, and 14 months. Extranodal low-grade MALT-type lymphomas can occur in the post-transplantation setting and generally develop years after transplant. As seen in immunocompetent patients, EBV appears to play no role in the pathogenesis of these lymphomas. These lymphomas appear to have more in common with MALT-type lymphomas in nonimmunocompromised patients than conventional PTLDs, although they occur in "at-risk" patients due to their immunosuppressive therapy. These lymphomas do not appear to be clinically aggressive. Recognition of MALT-type lymphomas in the post-transplantation setting as an indolent disease avoids unnecessary treatment.

Clonality of primary pulmonary lymphoproliferative disorders; using in situ hybridization and polymerase chain reaction for immunoglobulin

Primary pulmonary lymphoproliferative disorders (PLDs) are histologically divided into a neoplastic state of high and low grade malignant lymphoma (ML), and a reactive state of follicular bronchitis/bronchiolitis (FB) and lymphoid interstitial pneumonia (LIP). We reviewed 19 cases with PLDs, including 4 cases each of high and low grade B cell ML, 6 FB cases, and 5 cases of LIP. To clarify the clonality of the proliferating cells, we performed an immunohistochemical examination (IHC), in situ hybridization (ISH) for the immunoglobulin light chain and a polymerase chain reaction (PCR) analysis of the immunoglobulin heavy chain gene using DNA obtained from paraffin sections. In addition, a Southern blot analysis was also performed in 6 cases using fresh materials. In IHC, all ML were positive for L26 (CD20), while the monoclonality of the kappa light chain was observed in only one high grade case. However, using ISH we could detect the clonality in three of four high grade ML cases and in one of four low grade ML cases. In FB and LIP, no clonality of immunoglobulin by ISH was observed. In a PCR analysis for the immunoglobulin heavy chain gene, we could detect one or two prominent bands in all 8 cases of high and low grade ML. On the other hand, in all cases of FB and LIP, we could only detect either an oligoclonal or polyclonal population. In summary, the presence of monoclonality of ISH and/or PCR for the immunoglobulin heavy chain gene were limited in the neoplastic state, but not in the reactive state.

Molecular genetics of extranodal marginal zone (MALT-type) B-cell lymphoma

Mucosa-associated lymphoid tissue lymphoma is now classified as extranodal marginal zone B-cell lymphoma. We reviewed the current literature on the biological and genetic mechanisms that lead to the development and progression of this unusual lymphoma. Particular attention was given to the clinical and biological significance of the immunoglobulin genes rearrangement, that has been proposed and widely used both diagnostically and as a tool to monitor the response to antibiotic treatment.

PCR-based clonality analysis: a reliable method for the diagnosis and follow-up monitoring of conservatively treated gastric B-cell MALT lymphomas?

AIMS

We evaluated polymerase chain reaction (PCR) amplification of specific immunoglobulin heavy chain (IgH) gene rearrangements as a means of demonstrating monoclonality during follow-up of conservatively treated gastric MALT lymphoma, and compared the reproducibility of PCR on sequential frozen and paraffin-embedded endoscopic biopsies. We established an association between clonality detected by PCR and the histological observations.

METHODS AND RESULTS

Sixty-nine pairs of sequential frozen and paraffin-embedded endoscopic biopsies from 21 conservatively treated patients were graded according to the Wotherspoon-Isaacson histological scoring system, which provides a measure of diagnostic confidence on a scale 0-5. PCR amplification of the IgH gene was performed using FR3/JH and FR2/JH primers. 68/69 paired samples (98.5%) showed identical mono- or polyclonal PCR amplification patterns. Forty-seven out of 48 pairs of samples sharing similar histological features produced identical amplification patterns in both fresh and paraffin-embedded tissues. In comparison with the histological grading, monoclonality was detected in 64.2% and 41.6% of samples scored 5 and 4, respectively. Conversely, among 64 samples scored 0-3, a monoclonal pattern was observed only in two samples, one of which was from a patient who relapsed 9 months later.

CONCLUSIONS

PCR-based clonality analysis by demonstration of specific IgH gene rearrangement can be easily and reliably performed on both frozen and paraffin-embedded endoscopic biopsies. In conjunction with histological observation, this method can be used as a complementary tool to monitor MALT lymphoma regression during conservative treatment.

Evaluation and management of the "new" lymphoma entities: mantle cell lymphoma, lymphoma of mucosa-associated lymphoid tissue, anaplastic large-cell lymphoma, and primary mediastinal B-cell lymphoma

Non-Hodgkin's lymphomas (NHL) represent a major health problem worldwide, and incidence has been on the rise continuously for the last few decades. It is estimated that approximately 55,000 new cases of NHL will be diagnosed in the United States in 1998 and that slightly fewer than 25,000 patients will die of treatment failure or recurrent disease. The rising incidence of NHL is related not only to the acquired immunodeficiency syndrome epidemic but to also a steady increase in the number of cases diagnosed in older patients without immunosuppression. The new pathologic classification of NHL (revised European-American lymphoma classification, REAL) developed by the International Lymphoma Study Group (ILSG) is already resulting in more accurate disease-specific epidemiologic and clinical investigations. These studies have brought a new awareness of the existence and the relative prevalence of discrete NHL subtypes that appear to predominate among patients in different populations according to age, sex, geographic distribution, and predisposing conditions. This developing database has also the potential to result in the discovery of specific environmental causes, predisposing genetic factors, and therapeutic approaches. Some of the entities defined in the REAL classification, such as follicular lymphomas, diffuse B large-cell lymphomas, and T-cell lymphoblastic lymphomas, were already well described in the older classification systems (Kiel and Working Formulation). Others, such as mantle cell lymphoma, (MCL) anaplastic large-cell lymphoma (ALCL), lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), and primary mediastinal B-cell lymphoma (PMBCL) are relatively new members of the family, and accurate data on their clinicopathologic features and natural histories have only recently begun to emerge. This review presents in detail the most recent data on the clinical presentation of, diagnostic evaluation of, and treatment options for the most common of the new NHL entities: MCL, MALT lymphoma, CD30+ (Ki-1+) ALCL, and PMBCL. These four entities combined represent approximately 20% of all cases of NHL and exemplify well the broad clinicopathologic spectrum of NHL and the diagnostic and therapeutic challenges facing those who care for patients affected by these conditions.