Sebaceous carcinoma of the parotid gland in children: an immunohistochemical and ploidy study.

Sebaceous carcinoma (SC) is a rare malignancy, affecting mainly the periocular glands. To the best of the authors' knowledge, this is the first English-language report of parotid SC affecting children; two cases are presented. Immunohistochemical studies included 29 different antibodies (15 of these were cytokeratins, CKs). For each case, DNA ploidy status was determined using isolated nuclei stained with Feulgen and analysed using a DNA image cytometry system. Most of the tumour cells were positive for CKs AE1/AE3, 34B12, 5 and 7. The CK14 pattern depicted the monolayer of basal cells surrounding the islands of malignant tissue, while the more central sebaceous differentiated cells were negative. Epithelial membrane antigen was strongly positive in the well differentiated cells, while most of the basaloid peripheral cells were negative, and only a few cells were positive for carcinoembryonic antigen. beta catenin, E cadherin and C-erb B2 were expressed by most of the cells including the more differentiated sebaceous cells. Tumour cells were negative for muscle or myoepithelial markers, androgen, oestrogen and progesterone receptors. Both SCs were uniformly diploid, and showed low proliferative indices for p53, Ki-67 and Mcm-2, which is consistent with the good clinical course presented by these patients so far.