Figure 2: Pathogenesis and histopathology of hidradenitis suppurativa (a) The postulated three pathogenetic events in hidradenitis suppurativa. First, epidermal hyperkeratosis in the hair follicles with subsequent occlusion and dilation. Second, the follicular epithelial wall rupture occurs in the dermis and results in inflammatory cells infiltrate. Third, the formation of interconnecting sinus tracts is typical in the advanced stage of hidradenitis suppurativa. (b) The histopathologic change in hidradenitis suppurativa. The hair follicles reveal hyperkeratosis, hyperplasia, occlusion, dilation, or elongation. There is an inflammation around the hair follicles and apocrine glands. Besides, the dermis shows fibrosis. Rupture of the follicular wall can cause dense inflammatory cells aggregate and suppurative change in the dermis. The figure was drawn by using the commercial web-based software purchased from BioRender.com.