Phenotypic overlaps between pleomorphic malignant T-cell lymphomas and mixed-cellularity Hodgkin's disease

Area of Science:

• Hematopathology
• Oncology
• Immunohistochemistry

Background:

• Malignant lymphomas encompass diverse subtypes with overlapping histological features.
• Accurate differentiation of pleomorphic peripheral T-cell lymphomas (pPTCLs) and mixed-cellularity Hodgkin's disease (MCHD) is crucial for patient management.
• Classical histomorphology can be insufficient for definitive diagnosis in some cases.

Purpose of the Study:

• To objectively compare pPTCLs and MCHD using combined immunohistochemistry and quantitative morphometry.
• To identify discriminant features that aid in distinguishing these lymphoma subtypes.
• To evaluate the diagnostic utility of quantitative methods in challenging cases.

Main Methods:

• Combined immunohistochemistry on paraffin sections.
• Test-point analysis of tissue components.
• Semi-automated nuclear morphometry on semi-thin resin sections.

Main Results:

• Classical histomorphology remains a valid and primary diagnostic method.
• Quantitative features, including CD marker expression (CD45R0, CD43, CD45 in pPTCLs; CD30, CD15 in MCHD) and nuclear morphometry (LAC nuclear-profile areas), showed significant differences.
• Stepwise discriminant analysis revealed considerable overlap, with questionable cases exhibiting intermediate phenotypes.

Conclusions:

• Intra-group heterogeneity exists within both pPTCLs and MCHD.
• Indistinct borders and intermediate phenotypes complicate the distinction between these lymphoma categories.
• Quantitative analyses support and expand the understanding of lymphoma heterogeneity and diagnostic challenges.