P53 ONCOPROTEIN EXPRESSION IN CUTANEOUS LYMPHOPROLIFERATIONS

Background and Design: p53 overexpression has been reported in systemic lymphoproliferations, but our study is the first large series, to our knowledge, dealing with p53 expression in primary cutaneous lymphomas. p53 immunohistochemical detection using DO7 monoclonal antibody was performed in 54 cutaneous lymphoproliferative disorders, including 37 primary cutaneous T- or B-cell lymphomas. Results: No expression of p53 was found in 14 mycosis fungoides and seven pleomorphic T-cell lymphomas of either low or high grade of malignancy. Furthermore, no p53-positive cells were shown in low-grade B-cell lymphomas and in benign chronic dermatoses. p53 overexpression was seen over lymphomatous cells in 10 cutaneous lymphomas of high grade of T- or B-cell origin with two immunoblastic, three centroblastic, and five anaplastic lymphomas. Five of them occurred in human immunodeficiency virus-infected individuals, suggesting a possible interaction between p53 and viral proteins. p53 immunoreactivity was found over Reed-Sternberg-like cells in two cases of lymphomatoid papulosis. A labeling of keratinocytes located mainly in basal cell layers of the epidermis was observed in only five cases regardless of the lymphoma histologic subtype. Conclusions: p53 overexpression was not found in the most frequent primary cutaneous lymphomas, epidermotropic T-cell lymphomas. Alternatively, p53 immunoreactivity was observed in most primary cutaneous lymphomas of high grade of malignancy occurring in individuals either infected or not infected by human immunodeficiency virus. Molecular studies will determine if p53 overexpression is associated with p53 gene alteration and help to understand the role of p53 in primary cutaneous lymphoma genesis.