Transformation of MALT lymphoma to pure plasma cell histology following treatment with the anti-CD20 antibody rituximab

Coexistence of primary mediastinal MALT lymphoma and multiple myeloma like POEMS syndrome: A case report and literature review

RATIONALE

The coexistence of the extranidal marginal zone lymphoma (MZL) of mucosa-associated lymphoid tissue (MALT) and multiple myeloma (MM) is an exceedingly rare situation. The rare situation precludes any evidence-based guidelines for MZL or MM.

PATIENT CONCERNS AND DIAGNOSES

We presented a unique case of the coexistence of primary mediastinal MALT lymphoma and MM like polyneuropathy, organomegaly, endocrinopathy, M-protein, skin syndrome.

INTERVENTIONS AND OUTCOMES

The patient was first diagnosed with polyneuropathy, organomegaly, endocrinopathy, M-protein, skin syndrome in the department of neurology, then MM in the department of hematology, and the mediastinal MALT simultaneously coexisting with MM was found by biopsy in the department of thoracic surgery. The patient received combination therapy with rituximab and bortezomib followed by lenalidomide maintenance. To understand MZL lymphoma with plasmacytic differentiation better, we analyzed cases of MZL lymphomas with plasma cell neoplasms. Most of these cases were MZL lymphomas with light chain-restricted plasmacytic differentiation. The lymphomas relapsed with plasma cell neoplasms or transformed into plasma cell neoplasms after anti-lymphoma therapy.

LESSONS

The case demonstrated clinical complexity and the importance of the detailed assessment. The case and literature review demonstrated the value of detecting light chain-restricted plasmacytic differentiation for the treatment of MZL lymphoma with rituximab plus lenalidomide or bortezomib.

Thymic Extranodal Marginal-Zone Lymphoma of Mucosa-Associated Lymphoid Tissue: Pathological Features, 18F-FDG PET/CT Findings and Prognosis in 12 Cases

Purpose

Primary thymic extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) lymphoma is a rare type of MALT lymphoma. We aim to investigate the clinicopathologic features, ¹⁸F-FDG PET/CT findings and outcomes for patients with primary thymic MALT lymphoma; to explore the correlation between metabolic parameters and immunohistochemical phenotypes.

Methods

A retrospective single-center study enrolled 12 patients with primary thymic MALT lymphoma between 2010 and 2021. Nineteen ¹⁸F-FDG PET/CT scans were performed, and clinicopathologic and immunohistochemical characteristics, PET/CT imaging features, and outcomes were analyzed.

Results

The male-to-female ratio was 1. The median age at diagnosis was 40 (range 31–68). The long diameter of the lesions ranged from 3.5 to 15.7. Histopathological examinations revealed that the normal thymic lobular architecture was effaced by a diffuse lymphoid infiltrate, but residual Hassall corpuscles could still be identified, mostly with CD20+, PAX5+, CD3-, CD23-, CD10-, BCL-6-, cyclin D1-, EBER- and low Ki-67. The gene rearrangement indicated that the IGH gene but not TCR gene was found in 7 patients. Six initial PET/CT scans showed a mean SUVmax of 6.8 (range, 3.1–12.4), a mean MTV = 40.0 (range, 6.7–81.4), and a mean TLG = 144.3 (range, 19.7–286.4). During the follow-up period, there was no death except for the patient with DLBCL who died 59 months after diagnosis of primary thymic MALT. No significant correlation between SUVmax and Ki-67 index was observed (r = 0.355, P > 0.05).

Conclusion

Primary thymic MALT lymphoma should be considered in patients with multilocular cystic lesions with different degrees of ¹⁸F-FDG uptake in the anterior mediastinum. The results of this study showed no correlation between SUVmax and Ki-67 index.

Immunohistochemical CD20-negative change in B-cell non-Hodgkin lymphomas after rituximab-containing therapy

CD20^- change after rituximab-containing therapy is considered one of the main reasons of rituximab resistance of B-cell non-Hodgkin lymphomas (B-NHLs). However, the clinicopathological characteristics of B-NHL with CD20^- change are not entirely understood. In this study, 252 B-NHL patients who were CD20⁺ at initial diagnosis, whose diseases relapsed or were refractory after rituximab-containing therapy, and who were re-biopsied between 2000 and 2018, were included. The median number of rituximab administration was 11 (range, 1-48). Completely negative (cCD20^-) and partially negative (pCD20^-) change of CD20 was observed in 49 (20%) and 16 (6%) cases, respectively. Among cCD20^- and pCD20^- cases, 74% and 62% of the cases changed to CD20^- at the second relapse or later, respectively. Overall survival was significantly shorter in cCD20^- follicular lymphoma (FL) cases than in CD20⁺ FL cases. Seven histopathological patterns, such as CD20^- change without histological change, histological transformation (HT) to CD20^- diffuse large B-cell lymphoma, and proliferation of plasmablastic/plasmacytoid tumor cells, were associated with CD20^- change. HT occurred more frequently in FLs with CD20^- change than in FLs continuously expressing CD20 (P < 0.0001), regardless of the timing of HT. Nine out of 25 cases (36%) showed regain or heterogeneous regain of CD20 expression. In conclusion, 20% and 6% of the 252 B-NHL cases show cCD20^- and pCD20^- changes with 7 histological patterns after rituximab-containing therapy. Because changes in morphology and CD20 expression after rituximab-containing therapy vary, and recovery of CD20 expression is not rare, careful follow-up and re-biopsy in B-NHL patients are recommended.

A pilot phase II study of ofatumumab monotherapy for extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) lymphoma

These are the final results of the Ofatumumab in MALT lymphoma study (O-MA 1), a pilot phase II trial evaluating the capacity and safety of ofatumumab to induce objective responses in patients with Helicobacter pylori eradication refractory or extragastric MALT lymphoma. Ofatumumab was given at 4 weekly doses (1000 mg) followed by 4 doses at 2-month intervals starting at week 8. According to protocol, a total of 16 patients were recruited (median age 69 years; range 38-85). Thirty one percent (5/16) of patients had primary gastric MALT lymphoma while the remaining 69% (11/16) presented with extragastric manifestations. Seventy-five percent (12/16) had localized lymphoma and 4 patients disseminated disease. The overall response rate to treatment with ofatumumab was 81% (13/16), with the median time to best response being 5.5 months. In detail, 50% (8/16) achieved complete remission; 31% (5/16), partial remission; and 19% (3/16), disease stabilization as best response. However, 1 patient with gastric lymphoma and complete remission at second restaging had a relapse at final assessment but ongoing complete remission during further follow-up. Tolerability was excellent accept low-grade infusion reactions occurring in 86% (14/16). At a median follow-up time of 25 months only 1 patient has relapsed suggesting durable responses in the majority of patients. This pilot trial shows clearly that ofatumumab is active and safe for the treatment of MALT lymphoma.

18F-FDG PET/CT in gastric MALT lymphoma: a bicentric experience

PURPOSE

The role of 18F-FDG-PET/CT in evaluating gastric MALT lymphoma is still controversial. In the literature the detection rate of 18F-FDG-PET/CT in patients with gastric MALT lymphoma is variable, and the reason for this heterogeneity is not still clear. Our aim was to investigate the particular metabolic behavior of these lymphoma.

MATERIALS AND METHODS

Sixty-nine patients (26 female, 43 male) with histologically confirmed gastric MALT lymphoma who underwent a 18F-FDG-PET/CT for initial staging from two centers were included. The PET images were analyzed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax), lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio and compared with Ann Arbor stage, epidemiological (age, sex), histological (presence of gastritis, ulcer, H. pylori infection, plasmacytic differentiation, Ki-67 index), and morphological (tumor size, superficial lesions or mass-forming) characteristics.

RESULTS

Thirty-six patients (52 %) had positive PET/CT (average SUVmax was 9±6.7; lesion-to-liver SUVmax ratio 3.7±2.6, lesion-to-blood pool SUVmax ratio 4.8±3.3) at the corresponding gastric lesion; the remaining 33 were not 18F-FDG-avid. In the univariate analysis, 18F-FDG avidity was significantly associated with morphological features (mass forming p<0.001 and high maximum diameter p<0.001), Ann Arbor stage (p=0.010), and Ki67 index (p<0.001) and not correlated with age, sex, presence of gastritis, ulcer, Helicobacter pylori infection, and plasmacytic differentiation. In the multivariate analysis, the correlations with gross morphological appearance, Ann Arbor stage, and Ki-67 score were confirmed. SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio correlated significantly only with Ki67 index (p=0.047; p=0.012; p=0.042).

CONCLUSIONS

18F-FDG avidity was noted in 52 % of gastric MALT lymphoma and this avidity is correlated with gross morphological characteristics, tumor stage, and Ki-67 index. SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio are correlated only with Ki-67 index, and only lesion-to-liver SUVmax ratio was independently associated with Ki-67 score.

Extranodal Marginal Zone Lymphoma of the Lung: Evolution from an Underlying Reactive Lymphoproliferative Disorder

Extranodal Marginal Zone Lymphoma (ENMZL) of Mucosa-Associated Lymphoid Tissue (MALT) is a problematic and sometimes controversial diagnosis. While commonly seen in the stomach in the setting of chronic Helicobacter pylori infection, other extranodal sites, such as the lung, may also present with disease. ENMZL is clinically and morphologically heterogeneous; however, regardless of presentation, the etiology lies in the accumulation of lymphoid tissue in non-traditional sites. This phenomenon is typically secondary to an underlying inflammatory stimulus such as chronic infection or autoimmune states. The current case report details the clinical history of a patient with Sjögren syndrome over a four year period who eventually developed ENMZL. The patient initially presented with an atypical, but polyclonal, lymphoproliferative process diagnosed as lymphocytic interstitial pneumonia. Over time, the patient showed evolution to a monoclonal process with associated radiologic progression of disease. This evolution manifested as a dense lymphoid infiltrate with prominent plasmacytic differentiation and the development of a lung mass radiologically. This case contributes to the growing body of knowledge that suggests ENMZL lies along a biological spectrum of lymphoproliferative disorders whereby a benign, reactive process may eventually undergo malignant transformation. This evolution likely represents the acquisition of genetic abnormalities that allow autonomous proliferation in the absence of the initial immune stimulus. In practice, determining when this event occurs and, thus, distinguishing between reactive and neoplastic disorders within this spectrum may be difficult as no single clinicopathologic feature may be present to establish the diagnosis. This case further illustrates the importance of correlating the clinical, radiologic and pathologic data to evaluate patients with atypical pulmonary lymphoproliferative disorders and to allow the optimal management of their disease.

18F-FDG PET scanning in pulmonary amyloidosis

(18)F-FDG PET plays an important role in the evaluation of patients with lung malignancies but can lead to false-positive and false-negative results. Very little is known about (18)F-FDG PET scanning in amyloidosis.

METHODS

A computer-assisted search of medical records was conducted to identify subjects with pulmonary amyloidosis (confirmed by biopsy) who were seen at the Mayo Clinic during a 15-y period between January 1, 1997, and December 31, 2011, and had a PET scan available for current review.

RESULTS

Eighteen patients were diagnosed to have amyloidosis by lung biopsy (15 surgical, 2 transthoracic needle, and 1 bronchoscopic). The mean age of the patients was 64.8 y (range, 32-80 y). Seventeen patients had primary amyloidosis, including 5 with Sjögren syndrome, 1 with rheumatoid arthritis, and 1 with multiple myeloma. The most common abnormal findings on the chest CT scan were pulmonary nodules (n = 14), followed by cysts (n = 6) and reticular opacities (n = 4). Eight patients had positive (18)F-FDG PET results (intrathoracic (18)F-FDG uptake), including 4 patients with coexisting mucosa-associated lymphoid tissue lymphoma (maximal standardized uptake value [SUVmax] range, 3.1-6.7) and 1 patient with a pleural plasmacytoma (SUVmax, 7.2); the remaining 3 patients had amyloid only (SUVmax range, 2.1-3.2). Ten patients with negative PET results included 3 additional patients with mucosa-associated lymphoid tissue lymphoma.

CONCLUSION

Positive (18)F-FDG PET results, especially with an SUVmax of more than 3, in patients with pulmonary amyloidosis should raise suspicion about associated lymphoma or plasmacytoma, but negative PET results do not exclude the presence of such neoplasms.

Follow-up data of 10 patients with B-cell non-Hodgkin lymphoma with a CD20-negative phenotypic change after rituximab-containing therapy

Recently, a CD20-negative phenotypic change in CD20-positive B-cell non-Hodgkin lymphoma (B-NHL) after rituximab therapy was described. We report the follow-up data of 10 B-NHL patients showing this change after rituximab therapy. Ten patients (4 men and 6 women; median age, 57 y) with B-NHL who were initially CD20 positive and became CD20 negative after rituximab therapy were analyzed. Clinicopathologic features, including clinical course, CD20 expression, and histopathology, were examined. CD20 expression in lymphoma cells was evaluated using immunohistochemistry and/or flow cytometry. Histopathologically, diagnosis at initial presentation was follicular lymphoma (FL) in 7 patients; diffuse large B-cell lymphoma in 1; and chronic lymphocytic leukemia in 2. Six patients (60%, 3 FL, 1 diffuse large B-cell lymphoma, and 2 chronic lymphocytic leukemia patients) showed continuous CD20 negativity until 24 months after the phenotypic change. Three patients (30%) with FL regained CD20 expression within 1 to 7 months after detection of the CD20 change. Two patients (20%) with FL, including 1 who regained CD20 expression, showed heterogenous CD20 expression with a CD20-negative low-grade component and a CD20-positive large cell component. The overall response rate to therapy before the CD20-negative change was 70%. We reported the follow-up data of 10 B-NHL patients with a CD20-negative phenotypic change associated with rituximab-containing therapy. The most common histologic phenotypes were continuous CD20 negativity, recovery of CD20 expression within 7 months, and heterogenous CD20 expression. As the changes in morphology and CD20 expression after rituximab therapy vary widely, careful follow-up and rebiopsy are recommended.

Plasmacytic differentiation in MALT lymphomas following treatment with rituximab

Mucosa-associated lymphoid tissue (MALT) lymphomas are B cell neoplasms which commonly affect the gastrointestinal (GI) tract. Gastrointestinal MALT lymphomas rarely show plasmacytic differentiation (PCD), and limited data on the potential influence of the anti-CD20 antibody rituximab (R) on PCD exist in the current literature. We have retrospectively analyzed patients with GI MALT lymphomas treated with R-containing regimens because restaging is routinely performed by repeated biopsies with pathohistological response assessment. Twenty-one patients with GI MALT lymphoma were identified to have undergone R-containing therapy. In 19 patients, the lymphoma originated in the stomach, while the colon was the primarily affected organ in two cases. Four patients received R monotherapy and 17 combinations of R with various chemotherapeutic agents. Only two patients with gastric MALT lymphoma had PCD before initiation of therapy. In 7 of 19 patients (37%) without PCD at diagnosis, restaging revealed PCD after or while on treatment with R-containing regimens. Out of these seven patients, only one patient had a complete response as opposed to 10/12 without PCD. These data suggest that R or R-containing treatment regimens may not optimally eradicate the plasma cell component and thus lead to PCD in patients with GI MALT lymphoma. In view of this, rebiopsy and histological re-assessment appear mandatory in patients failing/relapsing after R-containing regimens.

Expression of CD19 and lack of miR-223 distinguish extramedullary plasmacytoma from multiple myeloma

AIMS

Extramedullary plasmacytoma (EMP) and multiple myeloma (MM) are both plasma cell (PC) tumours that are usually distinguished by clinical manifestations, but not by histopathological examination alone. However, EMP may express B-cell markers, such as CD79a and CD20, and MM may express germinal centre B-cell (GCBC)-associated microRNAs, such as miR-93 and miR-181b. Down-regulation of miR-30a or up-regulation of miR-223 is associated with the transition from GCBCs into PCs or memory B-cells, respectively. We studied B-cell markers and microRNAs to establish criteria that could distinguish EMP from MM.

METHODS AND RESULTS

Immunostains for the B-cell markers CD19, CD20, CD79a and PAX5 were performed. Expression levels of microRNAs 30a, 93, 181b and 223 were measured by real-time reverse transcription polymerase chain reactions. 73% of EMPs expressed CD19 whereas MM cases were negative. EMP and MM had similar levels of miR-30a, miR-93, and miR-181b, but EMP lacked expression of miR-223.

CONCLUSIONS

The presence of CD19 and lack of miR-223 suggested aberrant B-cell differentiation in EMP. Although the underlying mechanism for this differential expression was unclear, a CD19(+) /miR-223(-) phenotype could be used to distinguish EMP from the CD19(-) /miR-223(+) phenotype of MM.

Histological and immunophenotypic changes in 59 cases of B-cell non-Hodgkin's lymphoma after rituximab therapy

Rituximab is a chimeric monoclonal antibody that recognizes the CD20 antigen. It has been used to treat B-cell non-Hodgkin lymphoma (B-NHL), but recently rituximab resistance has been a cause for concern. We examined histological and immunohistochemical changes in 59 patients with B-NHL after rituximab therapy. The patients comprised 32 men and 27 women with a median age of 59 years. Pre-rituximab specimens comprised 34 follicular lymphomas (FL), 11 diffuse large B-cell lymphomas (DLBCL), 10 mantle cell lymphomas, two marginal zone B-cell lymphomas (MZBCL), and two chronic lymphocytic leukemias (CLL). CD20 expression in lymphoma cells was evaluated by immunohistochemistry or flow cytometry. Post-rituximab materials were taken a median of 6 months (4 days to 59 months) after rituximab therapy. Sixteen cases (27%) showed loss of CD20 expression with four histological patterns: pattern 1, no remarkable histological change (FL, 5; DLBCL, 3; and CLL, 2); pattern 2, proliferation of plasmacytoid cells (FL, 2; DLBCL, 1; and MZBCL, 1); pattern 3, transformation to classical Hodgkin's lymphoma (FL, 1); and pattern 4, transformation to anaplastic large cell lymphoma-like undifferentiated lymphoma (FL, 1). Loss of CD20 was unrelated to the interval of biopsies, treatment regimen, clinical response, and frequency of rituximab administration. Loss of CD20 within 1 month of rituximab therapy (3/14, 21%) and regain of CD20 (2/7, 29%) were not frequent. CD20-positive relapse with transformation occurred most frequently in cases of early relapse. In conclusion, B-NHL showed various histological and immunophenotypic changes after rituximab therapy, including not only CD20 loss but also proliferation of plasmacytoid cells or transformation to special subtypes of lymphoma.

Pathology and clinical course of MALT lymphoma with plasmacytic differentiation

BACKGROUND

The feature of plasmacytic differentiation (PCD) is present in up to 30% of patients diagnosed with mucosa-associated lymphoid tissue (MALT) lymphoma. To date, the influence of PCD on the clinical course of MALT lymphoma has not been assessed.

PATIENTS AND METHODS

Therefore, we have retrospectively analysed the clinical characteristics and the course of the disease in 34 (25%) patients with PCD as compared with 101 (75%) MALT lymphoma patients without this histological feature.

RESULTS

Patients with PCD had significantly more extragastric lymphomas [28 of 34 (82%) versus 54 of 101 (53%), P = 0.003] and a significantly lower rate of t(11;18) [2 of 26 (8%) versus 22 of 72 (31%), P = 0.02]. There was no significant difference of age at diagnosis (62 versus 64 years, P = 0.64), relapse rate (48% versus 37%, P = 0.27), estimated median time to progression (43 versus 65 months, P = 0.14), monoclonal gammopathy (50% versus 44%, P = 0.63), t(14;18) involving IGH/MALT 1 (11% versus 8%, P = 0.68), trisomy 3 (31% versus 27%, P = 0.69), trisomy 18 (8% versus 10%, P = 0.74) and the presence of autoimmune diseases between both groups (53% versus 37%, P = 0.09).

CONCLUSION

In conclusion, we found that PCD is predominantly found in extragastric MALT lymphoma but has no significant impact on clinical course and prognosis.

Activity of rituximab plus cyclophosphamide, doxorubicin/mitoxantrone, vincristine and prednisone in patients with relapsed MALT lymphoma

BACKGROUND

Various chemotherapeutic agents as well as the anti-CD20 antibody rituximab (R) have been tested in patients with mucosa-associated lymphoid tissue (MALT) lymphoma, but no standard chemotherapeutic regimen has emerged so far. Judging from the data obtained in various types of lymphoma, the activity of R appears to be enhanced by combination with chemotherapy. As no data on this topic exist for MALT lymphoma, we have retrospectively analysed our experience with R plus cyclophosphamide, doxorubicin/mitoxantrone, vincristine and prednisone (R-CHOP/R-CNOP) in patients with relapsed MALT lymphoma.

PATIENTS AND METHODS

A total of 26 patients were identified, 15 were administered R-CHOP while 11 patients were given R-CNOP due to age >65 years or pre-existing cardiac conditions. Cycles were repeated every 21 days, and restaging was performed after 4 cycles of therapy. In case of complete remission, 2 further cycles were administered for consolidation while patients achieving partial remission or stable disease after restaging were given 4 further courses.

RESULTS

A total of 170 cycles were administered to our patients (median 6, range 2-8). Twenty of the 26 patients (77%) achieved a complete remission and 6 (23%) a partial remission. Toxicities were mainly haematological, with WHO grade III/IV leukocytopenia occurring in 5 patients. After a median follow-up of 19 months (range 10-45), all patients are alive: 22 are in ongoing remission, while 4 have relapsed between 12 and 19 months after treatment.

CONCLUSIONS

Our data demonstrate a high activity of R-CHOP/R-CNOP in relapsing MALT lymphoma irrespective of prior therapy.

18F-Fluoro-deoxy-glucose positron emission tomography in lymphoma of mucosa-associated lymphoid tissue: histology makes the difference

BACKGROUND

The usefulness of 2-[fluorine-18]fluoro-2-deoxy-D-glucose Positron emission tomography (18F-FDG-PET) in lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is still a matter of debate, and conflicting results have been reported. We have evaluated whether the histological feature of plasmacytic differentiation (PD) might explain the heterogeneous behavior of MALT lymphoma regarding 18F-FDG uptake.

PATIENTS AND METHODS

A total of 35 patients with a diagnosis of MALT lymphoma referred to our PET unit were studied. Whole-body 18F-FDG-PET scans were carried out on a General Electrics advanced PET scanner 40 min after i.v. injection of 300-380 MBq 18F-FDG. Images were reconstructed iteratively. In areas with focally elevated FDG uptake, standard uptake values (SUVs) were calculated.

RESULTS

A total of 19 patients had MALT lymphoma with plasmacytic differentiation (pMALT), while MALT lymphoma without plasmacytic features was diagnosed in 16 patients. Sixteen of 19 patients with PD showed significant 18F-FDG uptake in involved sites (SUV: 3.5-11.7). By contrast, 13 of 16 patients with normal MALT lymphoma showed a false-negative 18F-FDG-PET result. Two of these patients disclosed no tracer uptake in the majority of involved sites apart from one single lesions, while three had a true-positive 18F-FDG-PET scan (SUV: 3.4-6.0).

CONCLUSIONS

18F-FDG-PET visualizes pMALT in a high proportion of patients, whereas FDG-PET results are significantly less reliable in typical MALT (P = 0.001). This finding may partly account for the heterogeneous results of 18F-FDG-PET-studies in MALT lymphoma.