Dominant ichthyosis vulgaris with an ultrastructurally normal granular layer.

It has been suggested that ultrastructural studies of keratohyalin granules in the granular layer of the skin can clearly distinguish the dominant type from the X-linked recessive type of ichthyosis vulgaris. The distinctive features are found in the granular layer and the keratohyalin granules. In the dominant form the granular layer is absent or reduced in size and the keratohyalin granules are minute and crumbly in appearance. In the recessive form the granular layer and keratohyalin granules are normal. A family which probably has dominant ichthyosis vulgaris is described. The stratum granulosum and keratohyalin granules as determined by both light and electron microscopy are normal. In view of the inconstant morphologic appearance of the stratum granulosum in ichthyosis vulgaris, it is suggested that distinction between the dominant and X-linked forms should not be based on the structural characteristics of the granular layer alone, but rather on a combined evaluation of the pedigree, clinical features and the appearance of the stratum granulosum.