• Mib1 in Mantle Cell lymphoma show increased proliferation versus other small B cell lymphomas
  • Ki-67(Mib-1) highlighting germinal centers in a tonsil.


  • MIB-1
  • Ki-67
  • MKI67


  • MIB-1

Technical InfoEdit

Staining PatternEdit

  • Nuclear

Expression in Normal TissuesEdit

  • Expressed in actively dividing/proliferating cells of all types. In other words, Ki-67 expression is seen in cells that are in any active phase of the cell cycle (G1, S, G2, and mitosis), but is not expressed in non-dividing/quiescent cells that are in G0 phase.

Expression in Neoplastic EntitiesEdit


Intermediate/Uncertain Malignant PotentialEdit


Expression in Non-Neoplastic EntitiesEdit

Pertinent NegativesEdit

This antigen is typically NOT expressed by the following entities:

    • Reactive, negative or atypical squamous epithelium of cervix [1]

Practical Uses / PanelsEdit

  • Ki-67 index is used as a approximate indicator of proliferative activity in various tumors. Some tumors use strict Ki-67 index cutoffs for diagnosis, but many tumors do not have strict criteria. The Ki-67 index is the number of Ki-67 positive tumor cells per 100 tumor cells, expressed as a percentage.
  • In the cervix, p16 can be used with Ki-67 (MIB-1) to differentiate between atrophy or reactive squamous epithelium (p16 focally + or negative, Ki-67 restricted to basal layer) from high-grade dysplasia (diffuse p16 +, Ki-67 diffuse +).[1][2]

Common PitfallsEdit

Related Links/Other ResourcesEdit


  1. 1.0 1.1 [1] Mod Pathol. 2003 Jul;16(7):665-73.
  2. Am J Surg Pathol. 2002 Nov;26(11):1501-7.

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