目的：探讨角化棘皮瘤（ｋｅｒａｔｏａｃａｎｔｈｏｍａ， Ｋ Ａ） 在细胞凋亡方面的生物学特点。方法：用末端脱氧核苷酰转移酶（ Ｔｄ Ｔ）介导的ｄ Ｕ Ｔ Ｐ 生物素缺口末端标记技术（ Ｔ Ｕ Ｎ Ｅ Ｌ） ，原位检测２０ 例角化棘皮瘤中凋亡细胞；应用免疫组织化学技术检测皮损部位ｂａｘ 和ｂｃｌ２ 基因产物的表达。结果： Ｋ Ａ 中８０ ％ （１６／２０） 瘤中心出现凋亡细胞。３０ ％ （６／２０） 肿瘤边缘ｂｃｌ２ 呈弱阳性染色。全部病例ｂａｘ 染色阳性。细胞凋亡指数与ｂａｘ 表达强度显著正相关（ ｒ＝ ０６８０ ， Ｐ＝ ０００１） ，与ｂｃｌ２ 表达强度显著负相关（ｒ ＝ － ０６１８ ， Ｐ＝ ０００４） 。结论：细胞凋亡为角化棘皮瘤的典型生物学特征，可能在 Ｋ Ａ 的自然消退中发挥重要作用。 Objective: To investigate the biological characteristics of keratoacanthoma (K A) in apoptosis. METHODS: Apoptotic cells in 20 cases of keratoacanthoma were detected in situ using terminal DNA deoxynucleotidyl transferase (Td T)-mediated d  U T P biotin gap end labeling (TU N E L); Immunohistochemistry was used to detect the expression of bax and bcl2 gene products in lesions. RESULTS: Apoptotic cells appeared in the center of 80% (16/20) tumors in KA. Thirty percent (6/20) of tumors showed weak positive staining for bcl-2. All cases were positive for bax staining. The apoptotic index was positively correlated with the intensity of bax expression (r = 0680, P = 0001), and was significantly negatively correlated with the expression of bcl2 (r = -0618, P = 0004). Conclusion: Apoptosis is a typical biological feature of keratoacanthoma and may play an important role in the natural regression of K A .