The Ki67 positivity rate of thymoma can be graded from I to IV, with 25%, 50% and 75% as the cut-off.
Ki67 antigen only exists in the late G1, S, M and G2 phases of the cell cycle and has a short half-life, so it is a reliable indicator of tumor proliferation.The higher Ki67 positivity indicates active tumor proliferation, poor tumor differentiation, high malignancy, easy to metastasize and recur, and a poorer prognosis.
Thymoma usually needs to be determined according to the naked eye and pathological examination results, and the Ki67 test for thymoma patients to determine its malignant degree and grading can provide a basis for chemotherapy, targeted therapy and so on.
Thymoma Ki67 can be categorized into grades I to IV. A positive rate of <25% is class I, a positive rate of 25-49% is class II, a positive rate of 50-74% is class III, and a positive rate of ≥75% is class IV. Classes III-IV are characterized by high expression, and classes I-II are characterized by low expression. Different pathology centers may have different defined values, and the reference values reported by local hospitals should be referred to for judgment.
It is recommended that patients with thymoma should combine the pathology report and other indicators of immunohistochemistry to comprehensively judge their condition and follow the doctor's instructions to choose the appropriate treatment plan.