Abstract: Objective To investigate the expression of phospho-Akt （p-Akt） in malignant melanoma （MM） and its relationship to the clinical and pathological features of MM. Methods Tissue samples were resected from 21 patients with MM collected from January 1994 to August 2006 in Sir Run Run Shaw Hospital. Samples from 21 patients with pigmented nevus served as control. Information about tumor staging, metastasis, invasion depth as well as patients′ age and postoperative 5-year survival rate was collected. Immunohistochemistry was used to measure the expression of p-Akt in the above samples. The correlation of p-Akt expression with the clinical features and prognosis of MM was evaluated. Results There was no expression of p-Akt in pigmented nevus tissue, and an increase was noticed in p-Akt expression in metastastic melanoma compared with primary melanoma （67% vs 56%, P < 0.05）. Furthermore, both the invasion depth of MM and age of patients with MM significantly correlated with p-Akt expression （r = 0.41, 0.53 respectively, both P < 0.05）. As the Kaplan-Meier survival curves showed, the strong expression of p-Akt was highly correlated with the post-operative 5-year survival rate of patients with MM （r = 0.41, P < 0.05）. Multivariate Cox regression analysis also revealed a strong correlation （OR = 2.586, 95% CI 0.906 to 7.382, P = 0.016） between the overexpression of p-Akt and survival rate in patients with high risk MM （invasion depth > 1.5 mm）. Conclusions The expression of p-Akt increases dramatically with the depth of invasion and with exacerbation of MM, but inversely correlated with the 5-year survival rate of patients. Consequently, p-Akt may help to predict the prognosis of patients with high risk MM.

Key words: melanoma, immunohistochemistry, p-Akt