p53 Protein and Ki-67 Antigen Expression in Keratoacanthoma and Keratoacanthoma-like Squamous Cell Carcinoma

Chon, Hyeong Jin; Son, Sook Ja; Kim, Dong Jun

Abstract

BACKGROUND: Differential diagnosis of keratoacanthoma(KA) from squamous cell carcinoma(SCC) is often difficult, especially when SCC has KA-like features(KA-like SCC). A number of recent studies have been attempted to separate these two entities with the use of immunohistochemical stains. But the results were inconsistent and the studies with KA-like SCC are rarely reported.
OBJECTIVES
The purpose of this study was to examine the expression patterns of p53 protein and Ki-67 antigen on KA and KA-like SCC using immunohistochemical staining method and to evaluate the usefulness of this method in distinguishing each other. METHODS: We performed immunoperoxidase staining(LSAB technique) using monoclonal antibody to p53 protein(PAb1801) and Ki-67 antigen(MIB1) on the formalin-fixed, paraffin-embedded biopsy specimens obtained from 12 patients with KA, 8 patient with KA-like SCC, and 10 patients with well-differentiated SCC.
RESULTS
The results were as follows; 1) There was a significant difference in the p53 expression between KA(25%) and SCC group (KA-like SCC=88%, SCC=100%). 2) Mean Ki-67 labeling index was slightly higher for SCC group(KA-like SCC=30.72%, SCC= 31.23%) than for KA(25.30%), but this difference was not statistically significant. 3) In Ki-67 expression, KA showed more pheriperal basal pattern(91%), whereas SCC group showed more diffuse pattern(77%).
CONCLUSION
Our results suggest that KA and SCC are distinct entities of different nature and that these immunohistochemical staining methods can be useful methods in differentiating KA-like SCC from KA.