Ki-67

Identifies a nuclear protein expressed in actively dividing cells (late G1, S, G2, and M phases) but absent in resting (G0) cells. It serves as a marker of cell proliferation, helping assess tumor growth rate and prognosis, with higher Ki-67 expression indicating more aggressive disease.

Synonyms

Turnaround Time

Global: 48 Hrs, Image Analysis (tech-only): 36 Hrs, Tech-Only (stain only): 24 Hrs

Methodology

IHC

Specimen Requirements

Tissue Block: Formalin-fixed, paraffin-embedded (FFPE) tumor block preferred.

Unstained Slides: Recommended 2 charged slides per stain requested (minimum of 1 slide per stain), baked or unbaked.

Fixation: Tissue must be fixed in 10% neutral buffered formalin for 6–72 hours.

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Storage and Transportation

Use cold pack for transport. Make sure cold pack is not in direct contact with specimen.

CPT Codes

88342x1 or 88341x1 (qualitative IHC) or 88360 (quantitative/semi-quantitative – manual) or 88361x1 (quantitative/semi-quantitative – computer assisted)