Primary mediastinal B-cell lymphoma, abbreviated PMBL or PMBCL, is a rare type of lymphoma that forms in the mediastinum (the space in between the lungs) and predominantly affects young adults. While it had previously been considered a subtype of diffuse large B-cell lymphoma;, the World Health Organization no longer classifies it as such, based on distinct clinicopathologic and molecular features. .

Diagnosis

Diagnosis requires a biopsy, so that the exact type of tissue can be determined by examination under a microscope. PMBCL is a distinct type of lymphoma that shares some features with both diffuse large B-cell lymphoma, and nodular sclerosing Hodgkin lymphoma (NSHL). Tumors that are even more closely related to NSHL than typical for PMBCL are called gray zone lymphoma.

Treatment

Treatment commonly begins with months of multi-drug chemotherapy regimen. Either R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) or DA-EPOCH-R (dose-adjusted etoposide, prednisolone, vincristine, cyclophosphamide, doxorubicin, rituximab) has been typical. Other, more intense, regimens may be more effective. Radiation therapy may be added, especially if chemotherapy does not seem sufficient on its own. Radiation may cause other health problems later, such as breast cancer, and there is some debate about the best approach to it. FDG-PET scanning is not as useful for predicting treatment success in PMBCL as it is in other lymphomas.

Prognosis

Most people with PMBCL are successfully treated and survive for many years. However, if the initial treatment is unsuccessful, or if it returns, the long-term prognosis is worse. Relapses generally appear within 12 to 18 months after the completion of treatment.

Epidemiology

This lymphoma is most commonly seen in women between the age of 20 and 40.