Abnormal keratohyalin-like forms in leukoedema.

Electron microscopic, histochemical and light-microscopic studies were carried out on biopsy specimens of 12 cases of leukoedema and on the desquamated epithelial cells of a further 50 examples. For comparison, similar observations were made of 4 examples of healthy cheek mucosa and 29 cases of a variety of pathological conditions of the oral mucosa. Only in leukoedema were a series of structures encountered which consisted of an aggregation of ribosomes and electron dense masses, or a network of electron-dense material, or an electron-dense network with a central dense core or a solid body with a few central cavities. Histochemical stains and RNA extraction studies showed that they are probably abnormal forms of keratohyalin granules and that ribosomes is an important component of their composition.