Cytokeratin expression in hidradenitis suppurativa and pilonidal sinus

Abstract

Purpose: The aim of our study was to elucidate the pathogenesis of hidradenitis suppurativa (HS) and pilonidal sinus (PS) by evaluating their cytokeratin (CK) expression. Methods: CK expression in HS (n = 15) and PS (n = 9) was studied immunohistochemically using six anti‐keratin antibodies. Results: In HS and PS, three types of epithelia were identified: infundibular‐like keratinized epithelium (type A), non‐infundibular keratinized epithelium (type B), and non‐keratinized epithelium (type C). Type A contained CK1, 10, and 14 similar to normal infundibulum, but it did not contain CK17. In types B and C, CK14, 16, and 17 were detected similar to that in normal outer root sheath. In tumor nests of squamous cell carcinoma derived from HS, CK 14, 17, and 19 were detected. Conclusions: Based on CK expression in HS and PS, sinus epithelium in HS and PS may possess characteristics of fragility, hyperproliferation, and undifferentiation.