Hair Shaft Normalization and Hair Growth in SPINK5-Syndromic Epidermal Differentiation Disorder (Netherton Syndrome) while on Treatment with Dupilumab: A Novel Therapeutic Approach for Trichorrhexis Invaginata - A Case Report.

Introduction: SPINK5-syndromic epidermal differentiation disorder (also known as Netherton syndrome [NS]) is a severe chronic genetic disorder characterized by skin inflammation, severe atopy, and trichorrhexis invaginata (TI). Causative Case Presentation: We diagnosed NS in a 67-year-old woman who had severe skin manifestations and a hair-growth defect since childhood. Scalp hair was sparse in the nuchal and temporoparietal regions. Trichoscopy of these areas showed numerous "bamboo" hairs that broke off during contact with the dermatoscope. We initiated treatment with dupilumab and optimized the topical therapy. At a 3-month follow-up, improvement of rash, pruritus, and quality of life was reported. Furthermore, the previously brittle short hair was replaced with longer hair and normal hair shafts in the previously affected areas. Conclusions: TI, as part of NS, has a variable presentation, biologics currently treating cutaneous inflammation, but little is known about their effects on hair biology. In this report, we show that dupilumab treatment not only proved efficient for control of skin inflammation and pruritus but was also associated with near-complete resolution of "bamboo" hair and promoted hair growth. Especially how alterations in the inflammatory response in NS can be linked to a structural defect have not been addressed in the current literature so far.