Cutaneous Ultrastructural Features of the Flaky Skin (Fsn) Mouse Mutation

The study examined the flaky skin (fsn/fsn) mouse mutation, an autosomal recessive genetic condition resembling human psoriasis vulgaris. Affected mice appeared normal at birth but later developed skin abnormalities such as hyperkeratotic plaques, acanthosis, and a thickened epidermis with sparse hair and scale accumulations. Hair shafts exhibited pits and striations, while nails were bent with surface irregularities. Microscopic analysis revealed increased epidermal thickness, mitochondrial aberrations, and neutrophil invasion. Abnormalities in keratohyalin and a high density of collagen fibers were also observed. These findings suggested that the flaky skin mouse mutation served as a natural model for studying human psoriasis vulgaris.