Colloid keratosis. Morphologic characterization of a nonspecific reaction pattern of squamous epithelium.

Colloid keratosis is characterized by homogeneous eosinophilic masses of variable size and number within the upper layers of squamous epithelia, including epidermis. It has been observed as the characteristic feature of many onychoses and inflammatory conditions of oral epithelium, and as an incidental finding in neoplastic and nonneoplastic lesions in the skin and respiratory tract. Its nature remains obscure, but knowledge at present suggests that it may represent a disorder of an early phase of keratinization. Current evidence supports the hypothesis that colloid keratosis represents a nonspecific cellular reaction pattern of squamous epithelium.