Immunohistochemical study of cytokeratins in hidradenitis suppurativa (acne inversa).

In 14 cases of hidradenitis suppurativa, cytokeratin (CK) expression was studied immunohistochemically, using six antikeratin antibodies against CK1, CK10, CK14, CK16, CK17 and CK19, respectively. The draining sinus tract epithelium of hidradenitis suppurativa lesions was divided into three components: infundibular-like keratinized epithelium (type A), non-infundibular keratinized epithelium (type B), and non-keratinized epithelium (type C). In type A samples, CK17 (which is found in normal infundibulum) was not detected, suggesting fragility of this epithelial type. Keratin expression in types B and C epithelia was similar to that observed in the outer root sheath in normal hair follicles. Our results suggest that the draining sinus epithelium may possess characteristics of fragility, undifferentiation and hyperproliferation, as shown with CK expression.