[White sponge nevus-type familial leucodysplasia of the oral cavity. Electron microscopic study of a case].

In a case of white sponge naevus type congenital buccal keratosis, electron microscopic study revealed severe disturbances in filamentogenesis which was insufficient (pale cells) or on the contrary excessive and anarchic (dark cells) and, to a lesser degree, corneal maturation. This was accompanied by slight abnormalities of the cellular junctions, rarely described in such a condition up to the present time. With regard to the delayed epithelial exfoliation typical of this condition, the manner and causes of its development are discussed in the light of ultrastructural findings.