Genetic mutations causing impaired function of gamma-secretase (NCSTN, PSEN1 or PSENEN genes)
Defective notch signaling pathway (a regulator of many cell processes)
Hormones (excess androgen activity)
Smoking (nicotine exposure)
Skin to skin friction
Systemic inflammation
Hidradenitis Suppurativa:
Pathogenesis and Clinical Findings
Other unknown genetic factors
Follicular occlusion
HS nodule
Epidermal layer
Dermal- Epidermal Junction
Dermal layer
Inflammatory cytokine- mediated activation of nociceptors
Inflammatory cytokines
Sebaceous gland
Apocrine sweat gland
Hair follicle
Pilosebaceous- apocrine unit
Changes in gene expression of hair follicle and apocrine gland anti-microbial peptides
Accumulation of corneocytes (dead keratinocytes) and sebum àfollicular occlusion and rupture
↑ Interleukin-36 (IL-36, a cytokine) Altered keratinocyte differentiation
Hair follicle hyperkeratinization
Abnormal structure and function of the pilosebaceous- apocrine unit
Infiltration of normal skin flora microbes, macrophages, dendritic cells, and Th17 cells
Increased density of nicotinic acetylcholine receptors in pilosebaceous-apocrine unit (see figure)
Mechanism not fully understood
Hyperhidrosis
Pain
Innate immune cells produce inflammatory cytokines: tumour necrosis factor alpha (TNF-α) and various interleukins (IL-1, IL-6, IL-12, IL-17, IL-22 and IL-23)
IL-17 promotes neutrophil migration into the skin
Formation of neutrophil extracellular traps (NETs)
B-cell activation and IgG autoantibody formation against skin tissue antigens
Scarring
Ongoing inflammation impairs wound healing
Granulocyte infiltration and activation, release of granulocyte colony-stimulating factor
Accumulation of keratin, purulent and/or serosanguinous fluid in dermis
Inflammatory papules, nodules, and abscesses
Pro-inflammatory cytokine-mediated response, leading to epithelial hyperplasia with increased fibrosis and collagen remodelling in the dermis
Formation of epithelial tissue tunnels in the dermis with two cavities on either end that open to the skin surface and fill with fluid or keratin
Hidradenitis Suppurativa
Chronic Inflammatory skin disease that occurs in areas with a high density of apocrine sweat glands, including the axilla, underneath the breasts, groin, and buttocks
Sinus tracts (dermal connections between lesions)
Double-ended comedones
Authors: Leah Johnston Reviewers: Mehul Gupta Lauren Lee Stephen Williams Ben Campbell Laurie Parsons* * MD at time of publication
Wound drainage and odour
Psychological distress
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published January 30, 2023 on www.thecalgaryguide.com