Gingival granular cell tumor of the newborn: immunoperoxidase investigation with anti-S-100 antiserum.

The gingival granular cell tumor (GGCT) of the newborn is a rare, benign tumor, most often observed in the canine area of the maxilla of female infants. The main histologic features are not controversial and involve the occurrence of sheets of granular cells and a prominent vascular component. Conversely, ultrastructural studies agree on limited features and give rise to different hypotheses of mesenchymal origin. S-100 immunoperoxidase investigation of one case shows that, unlike those of granular cell tumor (granular cell myoblastoma) granular cells of GGCT do not react positively for S-100 protein, thus suggesting that the GGCT and the granular cell myoblastoma have a different histogenesis. It confirms also the occurrence of smaller, isolated, spindled, nongranular S-100-positive cells of indeterminate nature, distributed at the periphery of some blood vessels.