Histologic findings in five cases of Kyrle's disease are described. Diagnostic features are: (1) A keratotic plug filling an epithelial invagination; (2) parakeratosis in parts of the plug; (3) basophilic cellular debris (not staining with elastic tissue stains) within the plug; and (4) abnormal (parakeratotic) keratinization involving the entire thickness of the epidermis in at least one region of the plug resulting in contact between keratinized cells and dermis. Associated findings are: (1) Areas of acanthosis and thinning of epidermis surrounding the plug; (2) presence of varying numbers of neutrophils at the site of contact between keratinized cells and dermis; (3) a lymphocytic and histiocytic infiltrate about the lesion; and (4) a mild perivascular lymphocytic inflammatory infiltrate in the upper dermis.
Constantine VS, Carter VH. Kyrle's DiseaseII. Histopathologic Findings in Five Cases and Review of the Literature. Arch Dermatol. 1968;97(6):633-639. doi:10.1001/archderm.1968.01610120023003