Abstract:

Objective To investigate the difference in cell apoptosis between keratoacanthoma and squamous cell carcinoma. Methods Ninety specimens were obtained from the lesions of 30 patients with regressing keratoacanthoma （rKA） and 30 patients with well-differentiated squamous cell carcinoma （wdSCC） as well as from the normal skin of 30 human controls. Immunohistochemistry was carried out to measure the expressions of B-cell leukemia/lymphoma 2 （Bcl-2）, cysteine-aspartic acid protease （Caspase）-3, second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pl （Smac/DIABLO） and inhibitor of apoptosis protein Livin. Results The Bcl-2 protein expression was significantly lower in rKA specimens than in normal control specimens （t = 3.1572, P < 0.05）. A lower expression of Caspase-3 protein was observed in rKA specimens compared with wdSCC specimens （t = 2.1364, P < 0.05）. The expression of Smac/DIABLO protein was significantly increased in normal control specimens than in rKA and wdSCC specimens （t = 7.6141, 9.5666, respectively, both P < 0.05）. Livin was absent in normal skin, but highly expressed in rKA and wdSCC specimens, and the difference was significant between the normal skin and lesional （rKA and wdSCC） specimens （t = 4.7913, 12.7737, respectively, both P < 0.05）. The expression of Livin protein was significantly reduced in rKA specimens than in wdSCC specimens （t = 7.9824，P < 0.05）. Conclusions Cell apoptosis plays a certain role in the natural regression process of KA. The detection of apoptosis-regulating proteins Caspase-3 and Livin are beneficial for the differentiation between rKA and wdSCC.

Key words: Immunohistochemistry