Congenital fibrous epulis: an undescribed fibrous lesion studied immunohistochemically and ultrastructurally.

Histological, immunohistochemical, and ultrastructural studies were done on a case of congenital gingival tumor with previously undescribed histopathological findings. The present lesion clinically mimicked a congenital epulis (congenital gingival granular cell tumor); however, it histologically consisted of densely packed collagen fibers forming numerous, well demarcated bundles surrounded by flattened cells with long slender cytoplasmic precesses. Immunohistochemical and ultrastructural findings suggested that these flattened cells embracing collagen bundles were fibroblastic in nature. Intracytoplasmic lysozomal granules could not be found in any cells of the lesion. Fibrous lesions similar to the present case have not been documented previously in the literature.