Immunohistochemical Study on the Expression of Mutated p53 Protein and Bcl-2 Protein in Melanocytic Lesions of Skin

ABSTRACT

To investigate the immunohistochemical expression of mutated p53 protein and bcl-2 protein in the cutaneous melanocytic lesion, 15 cases of compound nevus, 10 cases of congenital melanocytic nevus, 15 cases of primary malignant melanoma(4 cases less than 1.5 mm thick and 11 cases more than 1.5 mm thick), and 10 cases of metastatic malignant melanoma(7 cases in lymph node and 3 cases in soft tissue) were examined. All cases of compound nevi and of congenital melanocytic nevi showed no immunoreactivity for p53 protein. p53 protein overexpression was observed in 75%(3/4) wth primary malignant melanoma less than 1.5 mm thick, 81%(9/11) with primary malignant melanoma more than 1.5 mm thick, and 100%(10/10) with metastatic malignant melanoma. The difference in p53 protein overexpression was statistically significant between benign nevi and malignant melanoma(p<0.01). Bcl-2 protein expression was observed in 73%(11/15) with compound nevus, 70%(7/10) with congenital melanocytic nevus, 75% (3/4) in primary malignant melanoma less than 1.5 mm thick, 54%(6/11) with primary malignant melanoma more than 1.5 mm thick, and 40%(4/10) with metastatic malignant melanoma. These findings suggested that mutation of p53 gene may be an important mechanism in the development of malignant melanoma. Although bcl-2 protein was expressed in cutaneous melanocytic lesion, no correlation was found between p53 protein and bcl-2 protein expression in malignant melanoma.