Staining of non-inflammatory control (mammary) and hidradenitis suppurativa lesional (HS) biopsies. The biopsies were stained with (a) hematoxylin-eosin as well as (b) anti-filaggrin, (c) anti-involucrin, (d) anti-cytokeratin-10, and (e) anti-Ki-67 antibodies. Representative sections are shown and the value were mean ± SD (hematoxylin-eosin n = 5; filaggrin n = 5; involucrin n = 5; cytokeratin-10 n = 5; Ki-67 n = 9 patients; scale bar = 100 µM; black squares = mammary; black dots = HS; and black arrows = Ki-67(+) cells). values were calculated using Wilcoxon Mann–Whitney U Test, , , .