Aims Mantle cell lymphoma (MCL) has a highly heterogeneous clinical course ranging from indolent, to aggressive and rapidly progressive disease. Proliferation is a strong predictor for disease outcome. In routine clinical practice, Ki-67 expression is used as a measure of proliferation. However, several studies have documented a high degree of inter-laboratory and inter-observer variation with Ki-67 immunohistochemistry. Phosphorylation of histone H3 occurs specifically during mitosis and hence serves as a specific marker for cells in mitosis.
Methods and results We investigated phosphohistone H3 (PHH3) immunohistochemistry as a proliferation maker in 28 tissue biopsies of MCL and compared the PHH3 results (as evaluated by direct microscopic visualisation and image analysis-aided scoring) with morphological subtyping, mitotic counts and Ki-67 index. We found PHH3-mitotic count was about sixfold higher than H&E-mitotic count (mitoses in 10 high power fields). Furthermore, PHH3-mitotic count in aggressive morphological variants of MCL was significantly higher than in usual MCL. The PHH3-mitotic count showed a strong linear correlation with PHH3-mitotic index (percentage positive cells).
Conclusions We found PHH3 immunohistochemistry, a reliable mitosis-specific marker, in MCL. Performing precise counts and evaluating precise proliferation indices is easier with PHH3 immunohistochemistry. This contrasts with the conventional estimation of Ki-67 percentages by ‘eye-balling’.
- cell proliferation
- image processing
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Handling editor Runjan Chetty.
Contributors HM and KNN wrote the paper. HM and ME compiled the pathological data. HM and KNN designed the study and analysed the data.
Funding The work was supported by the National Institute for Health Research Imperial Biomedical Research Centre (RDF01). One of the authors was also partly supported by The Pathological Society of Great Britain and Ireland.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; internally peer reviewed.
Data availability statement All data relevant to the study are included in the article. Data is captured in the table.
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