MKI67 and Epidermal Inclusion Cyst: Serous EIC (S-EIC) reportedly arises in atrophic endometrium, especially in polyps, and recapitulates the morphological and immunophenotypical features of invasive serous carcinoma (i.e. high-grade nuclear atypia, scalloped profile, cellular tufting, high mitotic index, p53 mutant-type pattern, high Ki67 expression), which allow its identification [1, 4].