Primary B cell lymphoma of the mediastinum

DNA Methylation of Tumor Suppressive miRNAs in Non-Hodgkin's Lymphomas

DNA methylation is an epigenetic alteration leading to heritable phenotypic changes of cells with functional consequences. It is important in early embryonic development, stem cell differentiation, and tissue-specific gene expression. In normal cells, promoter-associated CpG islands (CGI) are generally unmethylated except in X-chromosome inactivation or genomic imprinting. In cancer, tumor cells are characterized by global hypomethylation but locus-specific hypermethylation of promoter-associated CGI, resulting in gene silencing. MicroRNAs (miRNAs) are short, non-coding RNA sequences of 18-25 nucleotides, which can repress the translational of multiple protein-coding mRNAs by sequence-specific binding to the 3'untranslated region. Depending on the genes targeted, miRNA can be tumor suppressive if an oncogene is repressed, or it can be oncogenic when a tumor suppressive gene is repressed. Recently, aberrant methylation of tumor suppressive miRNAs has been reported in different types of cancers including lymphomas. Herein, we review the recent literature of methylation of tumor suppressive miRNAs in different histopathologic subtypes of lymphomas, and discuss its potential diagnostic, prognostic, and therapeutic significance.

Primary Granulocytic Sarcoma of the Mediastinum

Primary granulocytic sarcoma (GS) is rare, and poses a diagnostic pitfall for both pathologists and oncologists. Previous literature showed that almost half of the patients with primary GS were misdiagnosed initially. We presented the clinico-pathological and radiological features of a patient with primary mediastinal GS, and discussed the differential diagnoses and clinical management.

Primary mediastinal large B-cell lymphoma: clinical study of a distinct clinical entity and treatment outcome in 20 patients: review of the literature

Primary mediastinal B-cell lymphoma (PMBCL) is a discrete subset of large B-cell lymphoma with unique clinicopathologic features. The question of optimal treatment emerges because it is an uncommon but not rare occurrence. A retrospective study was therefore conducted in a group of patients in Greece to evaluate the clinical features and treatment outcome in this disease. Twenty patients with PMBCL, with a median age of 42 years, treated at centers participating in the Hellenic Cooperative Oncology Group over the last 20 years, were reviewed. Thirteen (65%) had bulky disease at the time of presentation, 7 (35%) had superior vena cavae obstruction, and 15 (75%) had extranodal involvement. All received doxorubicin-containing chemotherapy, followed in 11 cases by mediastinal radiotherapy. With a median follow-up of 91 months, the median survival is 67.7 months. These data are consistent with those reported from other centers concerning the patient's characteristics, natural history, response pattern to chemoradiation therapy, and prognosis. Response to therapy proved of prognostic significance. A key question that remains is the prompt identification of patients who would benefit from innovative or more intensive therapies.

Temporary one-and-a-half ventricular repair to relieve lymphomatous obstruction of the pulmonary artery

Mediastinal lymphoma may infiltrate the conoarterial junction of the heart and cause life-threatening compression of the pulmonary artery. Partial debulking of the tumor along the left pulmonary artery and creation of a cavopulmonary anastomosis on the right pulmonary artery restored satisfactory perfusion of the lungs and unloading of the right ventricle in a 19-year-old woman. Remission of the tumor after chemotherapy allowed subsequent takedown of the cavopulmonary anastomosis.

Primary mediastinal large B-cell lymphoma: a clinicopathologic study of 43 patients from the Nebraska Lymphoma Study Group

PURPOSE

To investigate whether primary mediastinal large B-cell lymphoma (PMLBL) is a distinct clinicopathologic entity with a more aggressive course than other diffuse large B-cell lymphomas (DLBL).

MATERIALS AND METHODS

All patients with CD20-positive DLBL who presented with a mediastinal mass measuring at least 5.0 cm and were treated with curative intent were identified. A control group of 352 patients with nonmediastinal DLBL was selected for comparison.

RESULTS

The 43 patients with PMLBL had a male to female ratio of 20:23 and a median age of 42 years. Stage I/II disease was present in 58% of the patients, with only 9% having bone marrow involvement. A complete remission was achieved in 63% of the patients, and the 5-year overall and failure-free survivals were 46% and 38%, respectively. Among the clinical variables, an elevated serum lactate dehydrogenase level, a low performance score, more than one extranodal site, and an intermediate or high International Prognostic Index score were predictive of poor survival. When compared with the DLBL group, a younger median age was the only clinical feature that was significantly different in the PMLBL group.

CONCLUSION

The clinical features of PMLBL do not appear to be significantly different from those of nonmediastinal DLBL. Although the younger age of onset, slight female predominance, mediastinal location, and size of the mass may justify the recognition of PMLBL as a clinical syndrome, additional evidence is needed to define it as a distinct disease entity.