C-FOS PROTEIN EXPRESSION IN SPITZ NEVI, COMMON MELANOCYTIC NEVI, AND MALIGNANT MELANOMAS

The expression of c-fos protein was studied in formalin-fixed, paraffi n-embedded sections of 11 compound Spitz nevi (SNs), 16 ordinary compo und melanocytic nevi (MNs), and 17 malignant melanomas (MMs) using mon oclonal antibody MAB 1283 and an immunoperoxidase technique. Eleven (1 00%) SNs, 15 (94%) MNs, and 16 (94%) MMs showed positive reactions in some of the tumor cells (p = nonsignificant). In the majority of the r umors the staining was located in nuclei and graded as moderate to str ong in intensity. The percentages of positively stained cells did not differentiate the three types of tumor, although they were higher in t he melanocytic nevi. Most of the lesions with a significant dermal com ponent did not show stratification of staining with progressive descen t into the dermis. Positive staining for c-fos was also frequently fou nd in the normal skin constituents within and adjacent to the melanocy tic tumors. In conclusion, the pattern of expression of c-fos in routi nely processed specimens does not differentiate between SNs, MNs, and MMs.