Best Practices in CD30 Immunohistochemistry Testing, Interpretation, and Reporting: An Expert Panel Consensus

Area of Science:

• Hematopathology
• Oncology
• Immunohistochemistry

Background:

• CD30 testing is established for lymphoma diagnosis and emerging as a predictive biomarker.
• Current CD30 positivity definitions are descriptive, lacking established thresholds, leading to inconsistencies.
• Challenges include preanalytic variables, tissue processing, and interpretation variability.

Purpose of the Study:

• To develop best practice recommendations for reporting CD30 expression by immunohistochemistry in lymphoma biopsies.
• To harmonize practices across institutions for consistent CD30 assessment.
• To facilitate the evaluation of CD30's significance in clinical decision-making.

Main Methods:

• Literature review and expert group discussions involving hematopathologists and hematologist-oncologists.
• Formation of working groups focused on CD30 testing, readout, and interpretation.
• Review of panel recommendations and confirmation via an online survey.

Main Results:

• CD30 immunohistochemistry is required for differential diagnosis of classic Hodgkin lymphoma and peripheral T-cell lymphomas.
• Immunohistochemistry is the preferred methodology for CD30 testing.
• Any degree of CD30 expression should be reported.

Conclusions:

• Report CD30 expression for diagnostic purposes following established guidelines.
• For therapeutic decisions, report the estimated percentage of positive tumor cells.
• Descriptively report positive non-tumor cells when applicable.