Gingival granular cell tumors of the newborn. An ultrastructural and immunohistochemical study.

Gingival granular cell tumor of the newborn, or congenital epulis, is a rare congenital lesion of uncertain histogenesis located exclusively on the alveolar ridge with marked predilection for female infants. Although histologically similar to the more ubiquitous granular cell tumor or myoblastoma, ultrastructural and immunohistochemical studies support separate histogenetic pathways for the two lesions. A newborn female infant with three gingival granular cell tumors is described herein along with immunohistochemical and ultrastructural observations. There was positive immunostaining for vimentin but staining for S100 protein was uniformly negative. Immunocytochemical assay for estrogen and progesterone receptors was also negative. The findings indicate a mesenchymal origin and the demonstration of intermediate filaments with fusiform electron densities suggests that some of the granular cells have morphologic attributes of myofibroblasts.