IMMUNOHISTOCHEMICAL STUDY OF P53 PROTEIN EXPRESSION IN SPITZ NEVUS ASCOMPARED WITH OTHER MELANOCYTIC LESIONS

The accumulation of p53 protein was studied immunohistochemically on p araffin-embedded sections of 26 Spitz nevi (SNs), 26 primary invasive cutaneous malignant melanomas (MMs), 20 metastases of MM, and 17 ordin ary compound nevi (CNs), using monoclonal antibody BP53-12. Positive r eactivity was detected in some of the tumor cells in seven (35%) metas tatic MMs, all exhibiting strong nuclear staining; eight (31%) primary MMs, of which seven showed strong nuclear staining; two (7%) SNs, of which only one showed strong nuclear staining; and none of the CNs. Th e frequencies of the positively stained lesions in general, and the st rongly positively stained lesions in particular, in the MM and metasta tic MM groups were each statistically significantly higher than the re spective frequencies in the SN and CN groups. We believe that the immu nohistochemical detection of p53 protein with the use of monoclonal an tibodies such as BP53-12 on paraffin sections, especially when strong nuclear reactivity is demonstrated, may prove to be an adjunctive tool in the histopathologic differentiation of MM from SN.