Mediastinal Gray Zone Lymphoma: A Wider Category Than We Think?

Area of Science:

• Hematology
• Oncology
• Pathology

Background:

• Classical Hodgkin lymphoma (CHL) and primary mediastinal B-cell lymphoma (PMBCL) are distinct mediastinal B-cell lymphomas.
• Accurate classification is essential for appropriate treatment and prognosis.

Purpose of the Study:

• To identify and classify aggressive mediastinal B-cell lymphomas, including mediastinal gray zone lymphoma (MGZL).
• To define a minimum immunopanel for diagnosing MGZL.

Main Methods:

• Reviewed 92 mediastinal B-cell lymphomas using an extended immunopanel.
• Classified lymphomas as CHL, PMBCL, or MGZL based on specific immunophenotypic markers and transcription factor expression.
• Subclassified MGZL into MGZL-CHL and MGZL-PMBCL based on defined criteria.

Main Results:

• The number of identified MGZL cases increased from 9 to 28 with the extended immunopanel.
• MGZL subtypes (MGZL-CHL and MGZL-PMBCL) exhibited significantly poorer disease-free and overall survival rates compared to CHL and PMBCL.
• CHL and PMBCL showed disease-free survival rates of 86.8% and 69.2%, and overall survival rates of 97.4% and 80.8%, respectively.
• MGZL-CHL and MGZL-PMBCL showed disease-free survival rates of 33% and 40%, and overall survival rates of 66.7% and 60%, respectively.

Conclusions:

• Mediastinal gray zone lymphoma represents a wider spectrum of disease than previously recognized.
• An extended immunopanel is recommended for accurate identification of aggressive mediastinal B-cell lymphomas, including MGZL.