Presentation and management of primary mediastinal large B-cell lymphoma: a retrospective cohort analysis

Outcomes after allogeneic hematopoietic stem cell transplantation for adults with primary mediastinal B cell lymphoma: a SFGM-TC and LYSA study

Background: Despite therapeutic progress, 10 to 30% of adult patients with primary mediastinal B cell lymphoma (PMBCL) are primary refractory or experience early relapse (R/R). Allogeneic stem cell transplantation (allo-HSCT) thus remains a potentially curative option in this setting.Material and Methods: In this multicenter retrospective study, the outcomes of 33 French and Belgian adult patients allo-transplanted for R/R PMBCL between January 1999 and December 2018, were examined.Results: At allo-HSCT time, patients had received a median of 3 treatment lines, 50% of them were in complete response, 40% in partial response and 10% had a progressive disease. Forty-two percent of the donors were siblings and 39% matched related. The median follow-up for alive patients was 78 months (3.5-157). Considering the whole cohort, 2-year overall survival (OS), progression free survival (PFS) and graft-versus-host disease-free/relapse-free survival (GRFS) were 48% (95%CI: 33-70), 47% (95%CI: 33-68) and 38.5% (95%CI: 25-60) respectively. Cumulative incidence of relapse and non-relapse mortality rates were respectively 34% (95%CI: 18-50) and 18% (95%CI: 7-34). Disease status at transplant was the only factor predicting survivals, patients with progressive disease showing significant lower 2-year PFS (HR: 6.12, 95%CI: 1.32-28.31, p = 0.02) and OS (HR: 7.04, 95%CI: 1.52-32.75, p = 0.013). A plateau was observed for OS and PFS after 4 years with 10 patients alive after this date, suggesting that almost one third of the patients effectively salvaged and undergoing allo-SCT could be cured.Conclusion: This study indicates that allo-HSCT is a valid therapeutic option for R/R PMBCL, providing durable remissions.

Less Intensive Regimens May Still Be Suitable for the Initial Treatment of Primary Mediastinal B-Cell Lymphoma in Resource-Limited Settings

Primary mediastinal B-cell lymphoma (PMBCL) is an uncommon disease, consisting of 2–4% of non-Hodgkin lymphomas. Radiotherapy-free DA-EPOCH-R and R-CHOP plus radiotherapy (RT) have been the upfront standard regimens worldwide. However, performing DA-EPOCH-R in resource-constrained settings can be burdensome, especially in low/middle-income countries, where data on PMBCL are still largely unknown. We retrospectively analyzed 93 patients with PMBCL diagnosed between 2008 and 2018 with the intention of comparing the characteristics of the patients and the results obtained with each protocol and to verify if the use of less intensive chemotherapy is still possible to be used. The median age was 28 years, 59.1% were female, 42.3% were in advanced stages, and 92.1% were with bulky disease. DA-EPOCH-R (41.9%), R-CHOP (35.5%), and R-CHOEP (22.6%) were the regimens used, and no difference was observed in the characteristics of the patients. After four cycles of chemotherapy, complete response (CR), partial response (PR), and progressive disease (PD) rates were 40%, 55.7%, and 4.5%, respectively. At the end of treatment, metabolic CR and PD rates were 56.8% and 11.1%. RT was performed in 42.1% of DA-EPOCH-R, 75% of R-CHOP, and 83% of R-CHOEP, and switched PR to CR in 73.7%. Estimated 5-year PFS and OS were 77.2% and 77.4%, respectively. Only LDH levels remained independently associated with PFS, and type of treatment was not associated with OS, PFS, or relapse rate. Therefore, we conclude that in a resource-constrained setting, R-CHOP or R-CHOEP could be still safely adopted in upfront treatment for PMBCL.

Superior vena cava syndrome caused by mediastinal lymphoma: A rare clinical case

The superior vena cava syndrome refers to a medical emergency resulting from superior vena cava compression, which develops in 2%-4% of non-Hodgkin lymphomas. Primary mediastinal (thymic) large B-cell lymphoma is an unusual and aggressive non-Hodgkin lymphoma that can present with superior vena cava syndrome.

We report the case of a Caucasian 21-year-old female, who presented with acute superior vena cava syndrome, having started 2 weeks before. Chest computerized tomography disclosed an anterior mediastinal mass (18 × 14 cm). Thoraco-abdominopelvic magnetic resonance imaging was performed in order to differentiate compression versus mass invasion. A gross anterior mediastinal mass (109 × 60 × 105 mm) occupying the totality of the prevascular space was found, extending from the sternal furcula to the pericardium, fully embedding the superior vena cava. A computerized tomography guided biopsy was performed. Histopathological and immunohistochemical analysis was consistent with Primary mediastinal (thymic) large B-cell lymphoma.

Primary mediastinal (thymic) large B-cell lymphoma has unique clinicopathologic aspects and it should be considered in a young patient with Superior vena cava syndrome. Prompt recognition, a timely diagnosis and appropriate treatment are crucial for prognosis.

Primary Mediastinal (Thymic) Large B-Cell Lymphoma: Fidelity of Diagnosis Using WHO Criteria

PURPOSE

Diagnosing primary mediastinal (thymic) large B-cell lymphoma (PMBCL) is challenging because it is a clinicopathologic entity that shares characteristics with other lymphomas and lacks pathognomonic features. We sought to investigate the fidelity between a working diagnosis of PMBCL at our institution and the clinicopathologic criteria established within the 2017 World Health Organization (WHO) classification.

PATIENTS AND METHODS

Medical records and archived tissue of patients treated for stage I-II PMBCL from 1998 to 2018 were retrospectively reviewed for clinical and pathologic conformity with current WHO criteria. Disease was characterized as definitely PMBCL if all of the following were present: anterior mediastinal mass with or without lymph node involvement, no extranodal disease, B-cell antigen expression, Epstein-Barr virus negativity, and at least one supportive feature: female gender under age 40, bulky primary tumor, CD30 weakly positive, compartmentalizing alveolar fibrosis, lack of surface immunoglobulin expression, and MUM1 or CD23 positivity. Disease without supportive features or other pathologic findings more suggestive of other entities was characterized as equivocal for PMBCL. Lack of an anterior mediastinal mass, presence of distant lymph node involvement or extranodal disease, lack of B-cell antigen expression, or Epstein-Barr virus positivity were characterized as definitely not PMBCL. Clinical management and outcomes were also assessed.

RESULTS

Of 63 patients treated for presumed stage I-II PMBCL, 58 (92%) met the criteria for PMBCL. The most common reason for a discordant diagnosis was lack of an anterior mediastinal mass (n = 3). Two additional patients were characterized as having disease equivocal for PMBCL. In retrospect, one patient most likely had a mediastinal gray zone lymphoma due to CD15 positivity and another diffuse large B cell, not otherwise specified, at pathologic review. Five-year progression-free and overall survival were 67% (95% confidence interval, 54-77) and 81% (95% confidence interval, 68-89), respectively, for all patients.

CONCLUSION

Despite the complexity of the clinicopathologic criteria of PMBCL, most patients (92%) who were treated for stage I-II PMBCL at our institution appear to have been accurately diagnosed.