Significance of Staining Intensity in Ki-67 Proliferation Index in Meningiomas, and a Critical Review of the Literature on Proliferation Index Assessment.

Olivia C Brasher, James S Nix, Murat Gokden

Annals of clinical and laboratory science 2024 Mar

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Meningioma is the most common primary adult intracranial neoplasm, and proliferation indices (PI) rise with increasing grade from WHO CNS grade 1 to 3. Ki-67 immunohistochemistry (IHC) poses a variety of technical and interpretative challenges. Here, we specifically investigated the staining intensity and its effect on interpretation and final diagnosis. 124 high and low-grade meningiomas of various grades were blindly evaluated using different counting strategies (CS) based on the staining intensity of the nuclei as darkest (CS1), darkest+intermediate (CS2), and any staining (CS3) in hot-spots (HS) and in the context of overall proliferative activity (OPA). CSs in HS, OPA, and their average results were significantly different between low-grade and high-grade groups. PI obtained using CS3 yielded results that matched best with values expected for the corresponding WHO grade. CS had a profound impact on whether a LG meningioma would be diagnosed as one with a "high proliferation index." A large body of work exists on the counting methods, clinically significant cut-off values, and inter- and intra-observer variability for Ki-67 PI interpretation. We show that Ki-67 IHC staining intensity, which to our knowledge has not been previously systematically investigated, can have a significant effect on PI interpretation in settings that influence diagnostic and clinical management decisions. © 2024 by the Association of Clinical Scientists, Inc.

Citation

Olivia C Brasher, James S Nix, Murat Gokden. Significance of Staining Intensity in Ki-67 Proliferation Index in Meningiomas, and a Critical Review of the Literature on Proliferation Index Assessment. Annals of clinical and laboratory science. 2024 Mar;54(2):170-178