Atypical Phenotypes in Classical Hodgkin Lymphoma

Area of Science:

• Hematology
• Immunohistochemistry
• Oncology

Background:

• Classical Hodgkin lymphoma (cHL) exhibits a distinct immunophenotype in most cases.
• This includes expression of CD30, CD15, and PAX-5, alongside the absence of CD45 and T-cell markers.
• Variations in this pattern can complicate diagnosis.

Purpose of the Study:

• To outline the characteristic immunophenotype of classical Hodgkin lymphoma.
• To highlight atypical staining patterns that may lead to misdiagnosis.
• To emphasize potential diagnostic pitfalls in interpreting Hodgkin cell markers.

Main Methods:

• Immunohistochemical analysis of lymphoma cell markers.
• Evaluation of CD30, CD15, PAX-5, CD45, and B-lineage markers (CD20, CD79a, OCT-2, BOB.1).
• Comparative analysis of typical versus atypical staining patterns in classical Hodgkin lymphoma cases.

Main Results:

• Most classical Hodgkin lymphoma cases show CD30+, CD15+, PAX-5+, CD45-, T-cell marker negative immunophenotype.
• A subset of cases presents atypical staining, including CD15 negativity or expression of B-lineage markers.
• Misinterpretation of reactive cells like immunoblasts or histiocytes as Hodgkin cells is a significant diagnostic challenge.

Conclusions:

• Understanding the typical immunophenotype is crucial for diagnosing classical Hodgkin lymphoma.
• Awareness of atypical staining patterns and potential pitfalls is essential for accurate diagnosis.
• Careful interpretation of immunohistochemical markers is necessary to avoid misclassification and ensure appropriate patient management.