Sclero-Atrophic Reaction After Botulinum Toxin Injection

A 55-year-old woman experienced sclero-atrophy localized to the frontal scalp margin following a botulinum toxin type A injection for aesthetic purposes. Ten days post-injection, she developed a pruritic erythematous reaction, hair loss, and reduced follicular ostia, along with telangiectasias and folliculitis. A skin biopsy revealed sclerosis at the dermal-epidermal junction and reticular dermis, with chronic lymphocytic inflammation. The reaction might have been due to inappropriate injection placement or overdose, affecting the fibrous tissue rather than muscle. This case was notable as such histological and topographic features had not been previously reported in the literature.