Estimating the Burden of Illness of Relapsed Follicular Lymphoma and Marginal Zone Lymphoma in Ontario, Canada.

BACKGROUND: Many patients with advanced follicular lymphoma (FL) and marginal zone lymphoma (MZL) relapse after first-line chemotherapy. OBJECTIVE: To examine healthcare resource utilization (HCRU) and cost, treatment patterns, progression, and survival of patients with FL and MZL who relapse after first-line treatment, in Ontario, Canada. METHODS: A retrospective, administrative data study identified patients with relapsed FL and MZL (1 January 2005-31 December 2018). Patients were followed for up to three years post relapse to assess HCRU, healthcare costs, time to next treatment (TTNT), and overall survival (OS), stratified by first- and second-line treatment. RESULTS: The study identified 285 FL and 68 MZL cases who relapsed after first-line treatment. Average duration of first-line treatment was 12.4 and 13.4 months for FL and MZL patients, respectively. Drug (35.9%) and cancer clinic costs (28.1%) were major contributors to higher costs in year 1. Three-year OS was 83.9% after FL and 74.2% after MZL relapse. No statistically significant differences were observed in TTNT and OS between patients with FL who received R-CHOP/R-CVP/BR in the first line only versus both the first- and second- line. A total of 31% of FL and 34% of MZL patients progressed to third-line treatment within three years of initial relapse. CONCLUSION: Relapsing and remitting nature of FL and MZL in a subset of patients results in substantial burden to patients and the healthcare system.

Yttrium-90 Ibritumomab Tiuxetan is Cost-Effective Compared to Bendamustine + Rituximab in Low-grade Lymphomas.

BACKGROUND: Yttrium-90 ibritumomab tiuxetan [(90)Y-IT] is a CD20-targeted radio-immunotherapeutic agent. It has shown an excellent therapeutic activity with high tolerability against previously untreated follicular lymphoma (FL) and marginal zone B cell lymphoma (MZL). It is an attractive therapeutic option as the treatment schedule is short and convenient. The aim of our study is to determine the cost-effectiveness of (90)Y-IT in comparison to the standard-of-care bendamustine + rituximab (BR) in the first-line treatment of low-grade FL (LG-FL) and MZL in the real world. PATIENTS AND METHODS: We included all patients who were treated with standard-dose (90)Y-IT for previously untreated LG-FL and MZL at the Mayo Clinic Cancer Center (N = 51). A comparator arm with a historical cohort of previously untreated LG-FL and MZL patients who received BR was used (N = 92). RESULTS: Inverse propensity weighting was utilized to balance the 2 study arms. There were no differences in terms of overall response rate (100% vs. 98%, P = .18), complete response rate (94% vs. 95%, P = .91), or 5 years progression-free survival (76% vs. 75%, P = .63) between patients who received (90)Y-IT and BR, respectively. Within the first year, patients who received (90)Y-IT required an average of 4.5 fewer oncology clinic visits (P < .001), an average of 10 fewer days of therapeutic use (P < .001), and 40% less use of growth factors (P < .001) as compared to the BR group. The direct therapeutic cost of (90)Y-IT treatment was 54% less than that of 6 cycles of BR. CONCLUSION: The findings suggest that (90) Y-IT is more cost-effective than BR and is a viable alternative in up-front management of LG-FL and MZL.

Favorable radiation field decrease in gastric marginal zone lymphoma : Experience of the German Study Group on Gastrointestinal Lymphoma (DSGL).

PURPOSE: Long-term impact of stage-adapted field reduction in a large cohort of gastric marginal zone lymphoma (gMZL) patients treated conservatively with curative radiation therapy (RT). PATIENTS AND METHODS: Prospective analysis of paper records of 290 patients with stage IE-IIE gMZL, treated in 78 radiotherapeutic institutions in Germany from 1992-2013. Stage-adapted radiation fields decreased from extended field (EF) to involved field (IF) over the course of three consecutive prospective trials of the German Study Group on Gastrointestinal Lymphoma (DSGL). Treatment results were compared between the three cohorts. RESULTS: Overall collective with median age of 60 years, slight male predominance (m:f = 1.1:1) and ratio of disease stage I:stage II = 2.1:1. Median follow-up 6.4 years in total: 13.0 years in the first gastrointestinal study (GIT 1992), 8.2 years in the second (GIT 1996) and 4.7 years in the third study (DSGL 01/2003). Stage-adapted radiation field decrease together with further technological development led to reduced relative frequencies of acute/chronic adverse effects and until now was accompanied by lower disease recurrence. The third study design with smallest field size (IF in stage I, locoregional EF in stage II) achieved the best survival outcome at the 5­year follow-up (overall survival 92.7%, event-free survival 89.5% and lymphoma-specific survival 100.0%). Disease relapse observed in 10 patients. Cumulative incidence of disease-specific death was 1.7% of the followed patients. Primary disease stage associated with lymphoma-specific survival. CONCLUSION: Stage-adapted reduction towards IF in gMZL resulted in favorable adverse effects, local control and survival rates. These results support further decreases in modern RT of gMZL.

18F-FDG PET/CT for staging and response assessment of primary parotid MALT lymphoma with multiple sites involvement: A case report.

RATIONALE: Mucosa-associated lymphoid tissue (MALT) lymphoma is an extranodal low-grade B cell lymphoma that generally exhibits an indolent clinical course. Currently, the application of F-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) in MALT lymphoma is still controversial. Herein, we reported a case of using F-FDG PET/CT for staging and response assessment of primary parotid MALT lymphoma with multiple sites involvement. As far as we know, there are no similar case reports have been published before. PATIENT CONCERNS: A 71-year-old woman, who received mass resection twice during the past 2 years due to the repeatedly relapse of facial painless masses and diagnosed as reactive lymphoid hyperplasia by pathologic tests. However, the pathological diagnosis was then changed to primary parotid MALT lymphoma after left parotidectomy operation because of a new mass found in her left parotid. Four months later, the right eyelid of the patient swelled with a blurred vision. Then, F-FDG PET/CT scan was performed for staging, and the imaging results showed an abnormal increase of F-FDG uptake in multiple sites including bilateral ocular adnexal, lungs, pleura, occipital subcutaneous tissue, left kidney, and lymph nodes. DIAGNOSES: The patient was diagnosed as primary parotid MALT lymphoma with Ann Arbor stage of IVA based on the F-FDG PET/CT findings. INTERVENTIONS: The patient received 4 cycles of chemotherapy, followed by a partial metabolic remission (PMR), which was determined by interim F-FDG PET/CT, and finally additional 2 cycles of chemotherapy. OUTCOMES: The follow-up study illustrated that the patient had been alive and doing well at 12 months after chemotherapy. LESSONS: Although MALT lymphoma normally localizes in the primary organs, the involvement of multiple organs and lymph nodes is possible. The use of PET/CT demonstrated significant clinical values in the accurate staging and response assessment of F-FDG-avid MALT lymphoma. It is potentially useful for indicating the progress and transformation of MALT lymphoma, and guidance in localization of pathological biopsy. It is also helpful for clinicians to choose reasonable treatment strategy and improve the prognosis of patients.

Radiation therapy administration and survival in stage I/II extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue.

PURPOSE: To determine the factors associated with the use of radiation therapy and associated survival outcomes in early-stage marginal zone lymphoma of the mucosa-associated lymphoid tissue (MALT). METHODS AND MATERIALS: We extracted data on adult patients with stage I/II MALT lymphoma diagnoses between 1998 and 2010 recorded in the Surveillance, Epidemiology, and End Results (SEER) database. We studied factors associated with radiation therapy administration in a logistic regression model and described the cumulative incidence of lymphoma-related death (LRD) according to receipt of the treatment. The association of radiation therapy with survival was explored in multivariate models with adjustment for immortal time bias. RESULTS: Of the 7774 identified patients, 36% received radiation therapy as part of the initial course of treatment. Older patients; black or Hispanic men; white, Hispanic, and black women; and socioeconomically disadvantaged and underinsured patients had a significantly lower chance of receiving radiation therapy. Radiation therapy administration was associated with a lower chance of LRD in most sites. In cutaneous, ocular, and salivary MALT lymphomas, the 5-year estimate of LRD after radiation therapy was 0%. The association of radiation therapy with overall survival in different lymphoma sites was heterogeneous, and statistically significant in cutaneous (hazard ratio 0.45, P=.009) and ocular (hazard ratio 0.47, P<.0001) locations after multivariate adjustment. CONCLUSIONS: Demographic factors are associated with the use of radiation therapy in MALT lymphoma. Clinicians should be sensitive to those disparities because the administration of radiation therapy may be associated with improved survival, particularly in cutaneous and ocular lymphomas.

Comparative outcomes of rituximab-based systemic therapy and splenectomy in splenic marginal zone lymphoma.

Despite diagnostic and therapeutic advances, the majority of patients with splenic marginal zone lymphoma (SMZL) are still treated with splenectomy. We analyzed survival outcomes after surgery or rituximab-based systemic therapy in the Surveillance Epidemiology and End Results-Medicare database, using inverse probability of treatment weighting to minimize treatment selection bias. From the 657 recorded cases diagnosed between 2000 and 2007, with a median age of 77 years, we selected 227 eligible patients treated with splenectomy (68 %), rituximab alone (23 %), or in combination with chemotherapy (9 %) within 2 years from diagnosis. No significant difference between the groups was observed in the cumulative incidence of lymphoma-related death (LRD) at 3 years (19.6 % with systemic therapy and 17.3 % with splenectomy; hazard ratio [HR], 1.04; 95 % confidence interval [CI], 0.56-1.92; P = 0.90) or in the overall survival (HR, 1.01; 95 % CI, 0.66-1.55; P = 0.95). The 90-day mortality after splenectomy was 7.1 %. The rates of hospitalizations, infections, transfusions, and cardiovascular or thromboembolic events were higher after combination chemoimmunotherapy than after splenectomy. Conversely, there was no significant difference in most complications between groups treated with splenectomy or rituximab alone. The cumulative incidence of LRD after single-agent rituximab at 3 years was 18.7 % (95 % CI, 8.6-31.7). In conclusion, in SMZL patients over the age of 65 years, the risk of LRD and overall survival are similar with systemic therapy or splenectomy as initial therapy. Single-agent rituximab may offer the most favorable risk/benefit ratio in this population.

Ocular adnexal lymphoma: assessment of a tumor-node-metastasis staging system.

PURPOSE: To assess distribution, correlations, and prognostic effect of tumor (T), node (N), and metastasis (M) staging on relapse and survival. DESIGN: Retrospective clinical review. PARTICIPANTS: Sixty-three patients diagnosed with primary ocular adnexal lymphoma (OAL) between January 1986 and November 2011. METHODS: Complete ocular examination and systemic evaluation were performed. Patients were staged according to the American Joint Committee on Cancer (AJCC) seventh edition tumor-node-metastasis (TNM) clinical staging system for OAL and followed every 6 to 12 months (median follow-up, 27.9 months). MAIN OUTCOME MEASURES: Relapse defined as lymphoma recurrence in the initial site of presentation, the contralateral ocular adnexal structures, or other systemic site and overall survival. RESULTS: There were 40 men (63.5%). The median age was 65 years (range, 24-85 years). The affected site was the conjunctiva in 27 patients (42.9%), orbit in 38 patients (60.3%), and eyelid in 3 patients (4.8%). The histologic subtype was extranodal marginal zone lymphoma (EMZL) in 51 patients (81.0%). A total of 14 patients (23.3%) had T1, 42 patients (70.0%) had T2, 1 patient (1.7%) had T3, and 3 patients (5.0%) had T4 disease. A total of 48 patients (82.8%) had N0 disease, and 10 patients (17.2%) had N1-4 disease. M stage was M0 in 47 patients (81.0%) and M1 in 11 patients (19.0%). With advanced T stage, there was an increase in both N1-4 (P = 0.045) and M1 disease (P = 0.041). M1 disease was greater among patients with N1-4 disease compared with N0 stage (50.0% vs. 12.5%, P = 0.003). Overall, 18 patients (28.6%) relapsed and 6 patients (9.5%) died. In Cox analysis, relapse was not associated with T stage (hazard ratio [HR], 1.14 per 1 level increase, P = 0.71), N stage (HR, 1.47; P = 0.51 N1-4 vs. N0), or M stage (HR, 1.22; P = 0.76 M1 vs. M0). T stage was not associated with survival (HR, 0.86; P = 0.81), whereas N1-4 had marginally worse survival than N0 (HR, 5.35; P = 0.07), and M1 had worse survival than M0 (HR, 9.27; P = 0.008). CONCLUSIONS: The TNM staging system for primary OAL is useful for precise characterization of extent of local disease. Although T stage does not predict relapse or survival, N1-4 and M1 stages indicated less favorable survival. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

[Analysis of the clinical benefits and cost-effectiveness of performing a systematic second-look gastroscopy in benign gastric ulcer]. / Estudio del beneficio clínico y de coste-efectividad tras efectuar sistemáticamente una segunda gastroscopia en la úlcera gástrica benigna.

INTRODUCTION: We analyzed the need to routinely perform a second gastroscopy after an initial diagnosis of benign gastric ulcer. METHOD: A total of 226 consecutive cases of gastric ulcer were reviewed. Sensitivity (S), specificity (Sp), positive and negative predictive value (PPV and NPV) and the accuracy of the initial gastroscopy plus biopsy were analyzed, both overall and according to the initial endoscopist's experience (attending or resident physician). The diagnostic accuracy of the initial and second-look gastroscopies was compared. The number of second endoscopies required to diagnose a new case of malignant gastric ulcer and their cost was calculated, both overall and according to the endoscopist's experience. RESULTS: There were 178 benign ulcers (79%) and 48 malignant ulcers (21%). The initial gastroscopy (S: 87.2%; Sp: 100%; PPV: 100%; PNV: 96.7%; accuracy: 96.7%) was performed by an attending physician in 74% of the patients and by a resident physician in the remaining 26%. Diagnostic accuracy was higher for attending physicians than for residents (98.2% vs. 94.8%; p=0.18). The accuracy of second-look endoscopy was 100%, with a significant improvement when compared with the initial procedure (p=0.035). Three new cases of MALT lymphoma and three new cases of gastric adenocarcinoma were diagnosed and could be treated with curative intent. The number of second gastroscopies required to diagnose a new case of malignant gastric ulcer and their economic cost was: 37.3 (4,675 Euros) for the whole group, 55.2 (6,845 Euros) for attending physicians and 19.3 (2,393 Euros) for residents. CONCLUSIONS: Initial gastroscopy showed high diagnostic accuracy, which was slightly lower when performed by resident physicians. Second-look gastroscopy significantly improved the results, confirming the clinical benefit of this procedure in diagnosing potentially curable malignant lesions. The mean cost of each new diagnosis of malignancy was 4,675 Euros, which was three times lower if the initial gastroscopy was performed by a less experienced endoscopist.

[Assessment of BIOMED-2 assays for detection of clonal Ig gene rearrangements in mature B-cell lymphomas].

OBJECTIVE: To evaluate the efficiency of the BIOMED-2 PCR assay and its implication in the diagnosis of mature B-cell non-Hodgkin's lymphomas. METHODS: Clinical, morphological and immunohistochemical features of 72 cases of non-Hodgkin's lymphomas were studied, including 25 reactive lymphoid hyperplasia, 37 diffuse large B cell lymphomas (DLBCL) and 35 extranodal marginal zone lymphomas of mucosa associated lymphoid tissues (MALT lymphoma and in addition, 25 cases of reactive lymphoid hyperplasia were used as the controls). DNA was exacted from the paraffin embedded formalin fixed tissue blocks and the quality of DNA was assessed using the BIOMED-2 specimen control reaction. Adequate samples were then analyzed by BIOMED-2 for immunoglobulin heavy and kappa light chain rearrangements. RESULTS: Adequate DNA was obtained in 83 of 97 samples, including 60 mature B cell lymphomas and 23 reactive lymphoid hyperplasia. Clonal B-cell gene rearrangements were detected in 57 of 60 (95%) lymphomas. In contrast, clonal Ig gene rearrangements were not detected in any of the 23 cases of reactive lymphoid hyperplasia. CONCLUSION: BIOMED-2 assay is highly sensitive and specific for the detection of clonal B cell gene rearrangement using routine paraffin embedded formalin fixed specimens.

Assessment of disease dissemination in gastric compared with extragastric mucosa-associated lymphoid tissue lymphoma using extensive staging: a single-center experience.

PURPOSE: Molecular data and preliminary clinical findings have suggested mucosa-associated lymphoid tissue (MALT) lymphoma as a multifocal disease in a high percentage of patients. We report our findings with an extensive staging routine applied in patients diagnosed with MALT lymphoma at our institution. PATIENTS AND METHODS: A total of 140 consecutive patients (61 with gastric and 79 with extragastric MALT lymphoma) underwent staging according to a standardized protocol. Staging included gastroscopy with multiple biopsies, endosonography of the upper GI tract, computed tomography of thorax and abdomen, lymph node sonography, colonoscopy with multiple biopsies, otorhinolaryngologic assessment, magnetic resonance imaging of salivary and lacrimal glands, and bone marrow biopsy. All lesions suggestive of lymphoma involvement were subjected to biopsy, if accessible, and biopsies were evaluated for MALT lymphoma-specific genetic aberrations by means of reverse transcriptase polymerase chain reaction and/or fluorescent in situ hybridization. RESULTS: Fifteen (25%) of 61 patients with gastric MALT lymphoma had multiorgan involvement, with dissemination beyond the GI tract in six patients. By contrast, significantly more patients with extragastric MALT lymphoma had dissemination to another MALT organ (37 of 79 patients, 46%; P = .045). Nine of these 37 patients had dissemination to the stomach. Only three (2%) of 140 patients had bone marrow involvement. Multifocality was significantly associated with t(11;18)(q21;q21) in gastric lymphomas (P = .045) and with trisomy 18 in extragastric lymphomas (P = .011). CONCLUSION: Our findings suggest that MALT lymphoma frequently presents as a multifocal disease. Extragastric MALT lymphomas are significantly more prone to dissemination than gastric MALT lymphomas.

Histopathological assessment and immunohistochemical study of nasopharyngeal low grade MALT lymphoma.

INTRODUCTION: MALT lymphoma arises in a variety of body tissues, but most often in the stomach. Though relatively rare, these MALT lymphomas may arise within several sites in the head and neck, and often present diagnostic and therapeutic challenges. Immunohistochemical analysis are helpful in confirming the diagnosis between the MALT-lymphoma and the reactive lymphoid hyperplasia. MALT-type lymphoma demonstrated characteristic negative staining for CD3, CD5 and CD43, positive staining for CD20, and monotypic staining for either kappa or lambda light chain immunoglobulin markers, whereas reactive lymphoid hyperplasia all expressed B and T cell markers. MATERIAL AND METHODS: 41 Cases of nasopharyngeal masses were obtained from the files at pathology department, Mansoura Faculty of Medicine through the period from 2002 till 2006. 31 cases were corresponded histomorphologically to low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type and 10 patients with reactive lymphoid hyperplasia of the adenoid. Hematoxylin- eosin-stained slides were reviewed to confirm the diagnosis. Immunohistochemical studies were performed on formalin-fixed, paraffin-embedded sections using the labeled streptavidin-biotin-peroxidase complex method with DAB as chromogen. The following antibodies were evaluated CD20, CD3, Kappa, lambda and cytokeratin antibodies. RESULTS: All cases of low grade MALT lymphoma show lymphoepithelial lesion and proliferation of centrocyte like cells. 14 cases (45.1%) show subepithelial plasma cells. Dutcher bodies were demonstrated in 10 cases (32.2%). Monocytoid B-cells were seen in 12 cases (38.7%). Six (60%) out of the ten cases of adenoids show transmigrating lymphocyte without formation of lymphoepithelial lesion. All cases with MALT-type lymphoma expressed CD20 and not CD3 whereas 10 cases of adenoid, all expressed B and T cell markers. Immunohistochemical staining showed that 31 cases of low grade MALT lymphoma were positive for immunoglobin light chain (kappa or lambda) while 10 cases of adenoid were positive for both kappa and lambda light chain. CONCLUSION: Immunohistochemical analysis are helpful in confirming the diagnosis between the MALT-lymphoma and the reactive lymphoid hyperplasia of the nasopharynx.

Interobserver variation in the histopathological assessment of malt/malt lymphoma: towards a consensus.

BACKGROUND: The classification of mucosa associated lymphoid tissue (MALT) lymphoma is based on characteristic morphologic and immunophenotypic patterns, with distinctive chromosomal aberrations. The critical first step is diagnosis on evaluating H&E-stained sections. We performed an inter-observer study to determine the degree of agreement among pathologists in evaluating gastric lymphocytic infiltrates for MALT lymphoma. METHODS: A set of 41 H&E-stained gastric sections (36 endoscopic biopsies and 5 surgically resected sections) that ranged from simple gastritis to primary gastric lymphoma was reviewed separately and independently by 17 participants including hematopathologists, pathologists with a special interest in gastrointestinal pathology, and general pathologists. The participants were from the United States, Europe, and Japan. Results were entered into a standardized data collection form and the results were analyzed using kappa statistics. Monte Carlo simulation was used to adjust for multiple biases. RESULTS: Overall, interobserver reproducibility in the morphologic evaluation of gastric MALT was suboptimal. The kappa statistic was 0.3 for simple gastritis, low-grade MALT and for high grade MALT lymphoma. Monte Carlo simulation suggested that the degree of disagreement was directly related to the pathologist's experience in evaluating gastric biopsies for MALT lesions. However, after conjointly reviewing all cases, the Houston workshop agreed on findings that would increase the reproducibility of diagnosis, especially for pathologists with limited experience with this disease. These included the availability of macroscopic data, extensive sampling, the presence of lymphoepithelial lesions, immunophenotyping and particularly abnormal mucosa localization of B-cells, in addition to other molecular finding such as monoclonality and translocation t (11;18). The group also agreed on the need for standardizing the terminology currently used to facilitate future comparison between studies. CONCLUSIONS: Though the study shows poor agreement on morphologic MALT lymphoma categorization, the Houston workshop suggested recommendations that should increase the diagnostic accuracy and reproducibility of MALT lymphoma diagnosis. A follow up workshop will be organized to measure the diagnostic reproducibility for MALT lymphoma using the suggested recommendations.

Endoscopic ultrasound in the follow up and response assessment of patients with primary gastric lymphoma.

BACKGROUND: Endoscopic ultrasound (EUS) is considered the best technique for local staging of primary gastric lymphomas. Its role in the follow up of patients with gastric lymphoma following organ conserving strategies has not been established. AIM: To compare endosonographic response assessment with results of histological evaluation. PATIENTS AND METHODS: Thirty three patients with primary gastric lymphomas underwent pretreatment EUS and were followed endosonographically every 3-6 months after administration of organ conserving treatment modalities. A wall thickness of

Diffuse large B-cell lymphoma of the stomach: assessment of microsatellite instability, allelic imbalance, and trisomy of chromosomes 3, 12, and 18.

Several types of genetic aberrations including microsatellite instability (MSI), allelic imbalance (AI), and chromosomal trisomies have been reported in low-grade (LG) mucosa-associated lymphoid tissue (MALT)-type gastric lymphomas. Presence of such genetic alterations could be a discriminator between de novo large cell lymphoma and high-grade (HG) MALT-type lymphoma. We investigated 17 primary gastric large B-cell lymphomas with and without features of MALT-type lymphoma for MSI, AI, and presence of trisomy of chromosomes 3, 12, and 18. We studied resection specimens from 17 primary gastric extranodal diffuse large B-cell lymphomas. Cases classified as HG MALT-type lymphoma, based on either the presence of LG MALT-type lymphoma component in the background (L/H MALT) or large cell lymphoepithelial lesions (HG MALT), and diffuse large B-cell lymphoma (DLBCL-NOS) when no features of MALT were present. MSI was analyzed using fluorescently labeled polymerase chain reaction primers (D3S11, D6S262, D3S1261, D3S1262, D3S1265). Paired tumor and normal DNA samples were amplified, and PCR products were analyzed on a DNA sequencer (ABI PRISM 373XL) with GeneScan (Applied Biosystems, Foster City, CA). MSI was defined as a gain of a novel-length allele compared with the corresponding normal tissue. AI was assessed at locus 3q27 (D3S1262 and D3S1265). The cases were analyzed for the presence of trisomy of chromosomes 3, 12, and 18 using interphase fluorescence in situ hybridization. MSI was detected in 4 out of 15 (27%) cases from which DNA was amplifiable with all primers and all MALT-type lymphomas. In two cases (13%), MSI was present at two loci sufficient to be classified as high-frequency MSI (MSI-H); this was seen exclusively in HG MALT lymphomas (P = 0.04). In the remaining two cases, MSI was detected at a single locus (low-frequency MSI). Allelic imbalance at the locus D3S1262 was detected in 4 out of 17 (24%) cases. It occurred more commonly in stage IE lymphomas when compared with higher stages (P = 0.03), regardless of lymphoma subtype. Trisomy 12 was detected in 3 out of 17 cases (18%) exclusively in stage IE lymphomas (P = 0.08). MSI was uncommon and was found exclusively in MALT-type lymphomas. MSI-H was even less common but occurred in HG MALT lymphomas only. Allelic imbalance at 3q27 (D3S1262) and trisomy 12 were found more commonly in low-stage disease. The latter two findings are in concordance with the recent suggestion that the published variation in gain of chromosomal material in high-grade gastric lymphomas may be related to stage rather than to the subtype of lymphoma. Because of the relatively low frequency of MSI in the high-grade B-cell lymphomas of the stomach, this feature cannot be used to reliably discriminate between the histologic types of extranodal diffuse large B-cell lymphoma.